Artificial feather for badminton

Abstract

An artificial feather for a shuttlecock, which is provided with a feather shaft section made of a polymer alloy (B) and reinforcing fibers (A) containing at least carbon fibers (A1), and a feather wing section supported by the feather shaft section, and which is implanted in a circular ring shape in a base section of the shuttlecock, the artificial feather for shuttlecocks contains 1-50 parts by weight of reinforcing fibers (A) containing at least carbon fibers and 50-99 parts by weight of a polymer alloy (B) per 100 parts by weight of the total of the reinforcing fibers (A) and the polymer alloy (B), and the weight average fiber length (LwA1) of the carbon fibers (A1) is 0.5-7.0 mm. The artificial shuttlecock provided by the invention is excellent in impact strength and bending elastic modulus during water absorption.

Description

Technical Field

[0001] This invention relates to an artificial feather for use in shuttlecocks in badminton competitions. Background Technology

[0002] Compositions comprising reinforcing fibers and thermoplastic resins are widely used in sporting goods, aerospace, and general industrial applications due to their lightweight nature and excellent mechanical properties. These reinforcing fibers utilize metal fibers such as aluminum or stainless steel fibers, inorganic fibers such as silicon carbide fibers and carbon fibers, polyaramid fibers, or poly(p-phenylene oxide) Organic fibers such as PBO fibers are used, but from the viewpoint of balancing specific strength, specific stiffness, and lightweight, carbon fibers are preferred, with polyacrylonitrile (PAN) based carbon fibers being particularly preferred. Reinforcing fibers, when combined with thermoplastic resins, exhibit excellent reinforcing effects.

[0003] In addition, badminton shuttlecocks used in badminton include: shuttlecocks that use waterfowl feathers (natural feathers) as feathers (natural feathers), and shuttlecocks that use artificial feathers made by artificial means such as nylon resin (artificial feathers).

[0004] As is widely known, natural badminton shuttlecocks have the following structure: approximately 16 natural feathers from geese or ducks are used, with the ends of the feather shafts inserted into a hemispherical base made of cork covered with leather. The feathers used in natural badminton shuttlecocks are low in density and extremely lightweight. Furthermore, the feather shafts are highly rigid. Therefore, natural badminton shuttlecocks exhibit unique flight performance and a comfortable hitting feel.

[0005] However, the feathers used as raw materials for natural shuttlecocks are obtained from the aforementioned waterfowl, and not just any part of the waterfowl's feathers is suitable; only certain parts are appropriate for shuttlecocks. Therefore, the amount of feathers suitable for shuttlecocks that can be obtained from a single waterfowl is extremely limited, and the supply is unstable. Furthermore, their properties also vary.

[0006] On the other hand, the most well-known artificial shuttlecock is one with resin feathers molded in a ring shape. However, because each feather does not move independently like a natural shuttlecock, it is difficult to achieve the same flight performance as a natural shuttlecock.

[0007] Therefore, as described in the following patent document, an artificial feather that mimics feathers has been proposed. That is, an artificial feather shuttlecock with artificial feathers is proposed, wherein the artificial feathers have feather portions and feather shaft portions supporting the feather portions.

[0008] As a means to improve the durability and flight performance of artificial shuttlecocks, methods such as using fiber-reinforced thermoplastic resins can be cited (e.g., Patent Document 1). Furthermore, as a means to improve the rigidity and lightweight of artificial shuttlecocks, a method of using carbon fiber-reinforced thermoplastic resins on the inner part of the artificial shuttlecock has been proposed (e.g., Patent Document 2). In addition, as a means to improve the impact resistance of fiber-reinforced thermoplastic resins, a resin formed by adding a resin with reactive functional groups to a thermoplastic resin has been proposed (e.g., Patent Documents 3 and 4).

[0009] However, the artificial shuttlecocks obtained using these technologies, and the fiber-reinforced thermoplastic resins used in them, suffer from insufficient durability and deceleration performance as artificial shuttlecocks, resulting in inadequate impact strength and flexural modulus when absorbing water.

[0010] In the prior art, artificial shuttlecocks with high impact properties and flexural modulus when absorbing water have not yet been obtained in the form of fiber-reinforced thermoplastic resins with thermoplastic resins as the matrix, and there is a desire to develop such fiber-reinforced thermoplastic resin compositions.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2017-202001

[0014] Patent Document 2: Japanese Patent Application Publication No. 2012-75867

[0015] Patent Document 3: International Publication No. 2013 / 015111

[0016] Patent Document 4: International Publication No. 2010 / 107022 Summary of the Invention

[0017] The problem that the invention aims to solve

[0018] In view of the aforementioned problems of the prior art, the present invention aims to provide an artificial badminton shuttlecock with excellent impact strength and flexural modulus when absorbing water.

[0019] Methods for solving problems

[0020] To address the aforementioned issues, the present invention mainly comprises the following components.

[0021] (1) An artificial feather for badminton, comprising a feather shaft portion and feather wings supported by the feather shaft portion, the feather shaft portion being made of reinforcing fibers (A) containing at least carbon fiber (A1) and a polymer alloy (B), the artificial feather for badminton being inserted in a ring shape into the base portion of the badminton shuttlecock.

[0022] Relative to a total of 100 parts by weight of reinforcing fiber (A) and polymer alloy (B), the artificial feather for badminton shuttlecock comprises 1 to 50 parts by weight of reinforcing fiber (A) containing at least carbon fiber, and 50 to 99 parts by weight of polymer alloy (B), wherein the weight-average fiber length (LwA1) of the carbon fiber (A1) is 0.5 to 7.0 mm.

[0023] (2) The artificial feather for badminton as described in (1) comprises a continuous phase (P1) and a dispersed phase (P2), wherein the dispersed phase (P2) is dispersed in the continuous phase (P1) in a particulate form with a dispersion diameter of 10 to 1000 nm.

[0024] (3) The artificial feathers for badminton shuttlecocks as described in (1) or (2) contain particles with a particle size of 1 to 100 nm in the dispersed phase (P2).

[0025] (4) Artificial feathers for shuttlecocks as described in (1) or (2), wherein the shaft portion of the feather is made of a molding material.

[0026] The specific gravity of the molding material is below 1.21, and the unnotched Charpy impact strength is 75 kJ / m. 2 The water absorption rate after being placed in an environment of 80℃×95%RH for 24 hours is less than 1.5%, and the flexural modulus of elasticity when absorbing water at atmospheric equilibrium is greater than 5.3GPa.

[0027] Invention Effects

[0028] The artificial feathers for the artificial shuttlecock of the present invention comprise reinforcing fibers and a polymer alloy, and the reinforcing fibers are long, thus providing a high reinforcing effect and resulting in an artificial shuttlecock with excellent impact strength and flexural modulus when absorbing water. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the structure of an artificial feather for a badminton shuttlecock according to one embodiment of the present invention.

[0030] Figure 2 A schematic perspective view showing one morphological example of an artificial shuttlecock using the artificial feathers of the present invention. Detailed Implementation

[0031] The present invention will now be described in detail along with its embodiments.

[0032] The artificial feather for badminton of the present invention comprises at least reinforcing fibers (A) containing carbon fibers and polymer alloy (B).

[0033] The reinforcing fiber (A), in terms of the form of the starting material, is preferably a continuous bundle of reinforcing fibers, which imparts high mechanical properties to the molded article as a reinforcing material. The polymer alloy (B) is, for example, a matrix resin with high physical properties such as toughness, and has the function of firmly retaining the reinforcing fiber (A).

[0034] Regarding the types of fibers contained in the reinforcing fiber (A), there are no particular restrictions on other fibers as long as it contains at least carbon fiber, but it is preferable to further contain glass fiber as a fiber with high reinforcing effect. Depending on the desired reinforcing effect, it is preferable to use two or more types of these reinforcing fibers together.

[0035] The content of reinforcing fiber (A) in the composition of artificial feathers is preferably 1 to 50 parts by weight of reinforcing fiber (A) containing at least carbon fiber, relative to a total of 100 parts by weight of reinforcing fiber (A) and polymer alloy (B).

[0036] When the content of reinforcing fiber is less than 1 part by weight, the durability of the artificial shuttlecock decreases. The content of reinforcing fiber is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and even more preferably 15 parts by weight or more. Conversely, when the content of reinforcing fiber exceeds 50 parts by weight, it often leads to increased fiber entanglement, reduced dispersion of the reinforcing fiber in the molded product, and even increased fiber breakage, resulting in short fibers and reduced deceleration of the artificial shuttlecock. The content of reinforcing fiber is preferably 45 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 35 parts by weight or less.

[0037] The composition of the artificial feather contains a polymer alloy (B). The polymer alloy (B) of the present invention is preferably composed of at least two thermoplastic resins (Ba) that are different from each other and a second resin (Bb) having reactive functional groups.

[0038] By incorporating a thermoplastic resin (Ba) and a second resin (Bb) into the polymer alloy (B), the impact strength and flexural modulus of elasticity upon water absorption of the artificial badminton shuttlecock are improved, thus it is preferred. Furthermore, there are no particular limitations on the types of thermoplastic resin (Ba) and the second resin (Bb) contained in the polymer alloy (B), but as the thermoplastic resin (Ba), it is preferable to use a type of thermoplastic resin as described later that exhibits excellent mechanical strength. As for the second resin (Bb) having reactive functional groups, it is particularly preferable to use a type of thermoplastic resin as described later that exhibits excellent impact resistance. Depending on the desired effect, it is preferable to use two or more of these thermoplastic resins in combination. In this case, the combination of thermoplastic resins should be appropriately selected according to the desired properties.

[0039] <Thermoplastic Resin (Ba)>

[0040] Thermoplastic resin (Ba), preferably a thermoplastic resin with a molding temperature (melt temperature) of 200–450°C, includes polyolefin resins, polystyrene resins, polyamide resins, halogenated vinyl resins, polyacetals, saturated polyester resins, polycarbonate resins, polyarylsulfone resins, polyarylketone resins, polyphenylene ether resins, polyphenylene sulfide resins, polyaryletherketone resins, polyethersulfone resins, polyphenylene sulfide sulfone resins, polyarylate resins, and polyamide resins, all of which are equivalent to electrical insulators. Two or more of these can also be used. From the viewpoints of processability, mechanical properties, and lightweight, polyamide resins are preferred.

[0041] Here, polyamide resin refers to a resin that uses amino acids, lactams, or diamines and dicarboxylic acids as main raw materials. Representative examples of such main raw materials include: amino acids such as 6-aminohexanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and p-aminomethylbenzoic acid; lactams such as ε-caprolactam and ω-laurolactam; tetramethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, etc.; aromatic diamines such as m-phenylenediamine and p-phenylenediamine; 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1-amino-3-aminomethyl-3,5-dicarboxylic acid, etc. Alicyclic diamines such as 5-trimethylcyclohexane, bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine, and aminoethylpiperazine; alicyclic dicarboxylic acids such as adipic acid, octanoic acid, azelaic acid, sebacic acid, and dodecanoic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, sodium isophthalate-5-sulfonate, hexahydroterephthalic acid, and hexahydroisophthalic acid; and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,2-cyclohexanedicarboxylic acid. Two or more of these can also be used.

[0042] From the viewpoint of excellent mechanical properties, polyamide resins with melting points above 200°C are particularly useful as thermoplastic resins (Ba). Specific examples include: polycaprolactam (Nylon 6), polyhexamethylene adipamide (Nylon 66), polycaprolactam / polyhexamethylene adipamide copolymer (Nylon 6 / 66), polybutadiene adipamide (Nylon 46), polyhexamethylene decanediamide (Nylon 610), polyhexamethylene dodecyl diamide (Nylon 612), polydecyl decanediamide (Nylon 1010), polydecyl decanediamide (Nylon 1012), polydodecyl dodecyl diamide (Nylon 1212), polyundecylamide (Nylon 11), polydodecylamide (Nylon 12), polyhexamethylene terephthalamide / polycaprolactam copolymer (Nylon 6T / 6), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (Nylon 6T / 6), etc. Poly(hexamethylene adipamide) / poly(hexamethylene isophthalamide) copolymer (Nylon 66 / 6I), poly(hexamethylene adipamide) / poly(hexamethylene terephthalamide) / poly(hexamethylene isophthalamide) copolymer (Nylon 66 / 6T / 6I), poly(hexamethylene terephthalamide) / poly(hexamethylene isophthalamide) copolymer (Nylon 6T / 6I), poly(hexamethylene terephthalamide) / polydodecanoamide copolymer (Nylon 6T / 12), poly(hexamethylene terephthalamide) / poly(2-methylpentamethylene)diamine copolymer (Nylon 6T / M5T), poly(dimethylphenylene adipamide) (Nylon XD6), poly(nonadiamine terephthalamide) (Nylon 9T), and copolymers thereof. Two or more of these may also be used. Among these, nylon 6, nylon 66, nylon 610, nylon 11, nylon 12, and nylon 9T are more preferred.

[0043] There are no particular limitations on the degree of polymerization of these polyamide resins. Preferred polyamide resins are those in which the relative viscosity of a solution containing 0.25 g of polyamide resin dissolved in 25 ml of 98% concentrated sulfuric acid is measured at 25°C and is in the range of 1.5 to 5.0. More preferably, polyamide resins in the range of 2.0 to 3.5 are preferred.

[0044] <Second resin (Bb) with reactive functional groups>

[0045] The resin used as the basis for the second resin (Bb) having reactive functional groups is not particularly limited and can be selected from, for example, polyamide, polyester, polyphenylene sulfide, polyphenylene ether, polycarbonate, polylactic acid, polyacetal, polysulfone, polytetrafluoroethylene, polyetherimide, polyamideimide, polyimide, polyethersulfone, polyetherketone, polythioetherketone, polyetheretherketone, polyethylene, polypropylene, polystyrene or ABS and other styrene-based resins, rubber polymers, polyepoxides, etc. Furthermore, at least one resin different from the aforementioned polyamide resin (Ba) can be used. From the viewpoint of ease of introducing reactive functional groups, the resin used as the basis for the second resin (Bb) is more preferably selected from polyolefin resins such as polyethylene resin and polypropylene resin, styrene-based resins, and rubber polymers. Moreover, from the viewpoint of imparting impact absorption, rubber polymers are more preferably selected.

[0046] Rubber-like polymers contain polymers with low glass transition temperatures, and are polymers in which some molecules are bound together by covalent bonds, ionic bonds, van der Waals forces, entanglement, etc. The glass transition temperature of rubber-like polymers is preferably below 25°C. If the glass transition temperature exceeds 25°C, there is a risk of poor impact resistance.

[0047] Examples of rubbery polymers include, for instance, random copolymers and block copolymers of polybutadiene, polyisoprene, styrene-butadiene, hydrides of these block copolymers, diene rubbers such as acrylonitrile-butadiene copolymers and butadiene-isoprene copolymers, random copolymers and block copolymers of ethylene-propylene, random copolymers and block copolymers of ethylene-butene, copolymers of ethylene with α-olefins, copolymers of ethylene with acrylic acid and ethylene with methacrylic acid, ethylene-unsaturated carboxylic acid copolymers, ethylene-acrylates, ethylene-methacrylates, and other ethylene-unsaturated carboxylic acid ester copolymers. Preferred examples include ethylene-acrylic acid-acrylic acid metal salts, ethylene-methacrylic acid-methacrylic acid metal salts and other ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid metal salt copolymers, acrylate-butadiene copolymers, acrylic elastic polymers such as butyl acrylate-butadiene copolymers, ethylene-vinyl acetate copolymers and other copolymers of ethylene and fatty acid vinyl esters, ethylene-propylene-ethylene-neobornene copolymers, ethylene-propylene-hexadiene copolymers and other ethylene-propylene non-conjugated diene terpolymers, butene-isoprene copolymers, chlorinated polyethylene, polyamide elastomers, polyester elastomers and other thermoplastic elastomers.

[0048] From the viewpoint of obtaining excellent impact strength, when using thermoplastic resins (Ba), it is preferable to use ethylene-unsaturated carboxylic acid ester copolymers or random copolymers and block copolymers of ethylene-propylene, random copolymers and block copolymers of ethylene-butene, and copolymers of ethylene and α-olefins.

[0049] The unsaturated carboxylic acid ester in the ethylene-unsaturated carboxylic acid ester copolymer is preferably a (meth)acrylate. Specific examples of unsaturated carboxylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, etc. Here, "(meth)acrylate" refers to "acrylic acid or methacrylic acid". There is no particular limitation on the weight ratio of ethylene component to unsaturated carboxylic acid ester component in the copolymer, but it is preferably in the range of 90 / 10 to 10 / 90, more preferably in the range of 85 / 15 to 15 / 85. There is no particular limitation on the number average molecular weight of the ethylene-unsaturated carboxylic acid ester copolymer, but from the viewpoint of flowability and mechanical properties, it is preferably in the range of 1000 to 70000.

[0050] The reactive functional groups contained in the second resin (Bb) are not particularly limited as long as they can react with the functional groups present in the thermoplastic resin (Ba), but preferably include those selected from amino, carboxyl, metal salts of carboxyl, hydroxyl, epoxy, acid anhydride, isocyanate, and mercapto groups. At least one of zolyl, sulfonic acid, etc. Among them, the group selected from amino, carboxyl, metal salts of carboxyl, epoxy, acid anhydride, and... The zoline group is preferred because of its high reactivity and fewer side reactions such as decomposition and cross-linking.

[0051] As a method for introducing anhydride groups into a rubber polymer, it can be carried out by known techniques without particular limitations. For example, methods such as copolymerizing anhydrides such as maleic anhydride, itaconic anhydride, norbornene anhydride, citraconic anhydride, and 1-butene-3,4-dicarboxylic anhydride with monomers that are raw materials for rubber polymers, or grafting anhydrides onto rubber polymers can be used.

[0052] There is no particular limitation on the number of functional groups in each molecular chain of the second resin (Bb) having reactive functional groups, but it is generally preferred to have 1 to 10, and preferably 1 to 5 in order to reduce side reactions such as cross-linking.

[0053] Polymer alloy (B) is formed from a thermoplastic resin (Ba) and a second resin (Bb) having reactive functional groups. Polymer alloy (B) is obtained by melt-blending the thermoplastic resin (Ba) and the second resin (Bb) having reactive functional groups. By using the second resin (Bb) with reactive functional groups, during the melt-blending of the thermoplastic resin (Ba) and the second resin (Bb), the polymer alloy (B) contains a continuous phase (P1) and a dispersed phase (P2). Even after melt-blending is completed, a portion of the reactive functional groups remains reactive and remains in the second resin (Bb). This highly controlled structure of the particles formed from the second resin (Bb) significantly contributes to improved impact resistance.

[0054] The dispersed phase (P2) is preferably dispersed in the form of particles with a particle size of 10 to 1000 nm. When the number average particle size is less than 10 nm, the impact resistance characteristic of this invention cannot be exhibited; when it exceeds 1000 nm, there is a risk of reduced rigidity characteristic of this invention. By containing particles formed from a second resin (Bb) with a highly controlled structure, a composition of artificial feathers with an excellent balance of rigidity and impact resistance can be obtained, and the durability and deceleration performance of artificial shuttlecocks using it can be improved.

[0055] Furthermore, the artificial shuttlecock of the present invention preferably contains particles with a particle size of 1 to 100 nm in the dispersed phase (P2). By controlling the structure within the dispersed phase as described above, a composition of artificial feathers with a superior balance between rigidity and impact resistance, and an artificial shuttlecock using the same, can be obtained.

[0056] Furthermore, regarding morphological observation methods, well-known techniques can be employed. For example, one method involves cutting the center of the test specimen into 1-2 mm square sections, staining the reactive functional group-containing second resin (Bb) with ruthenium tetroxide, and then using an ultramicrotome to obtain ultrathin sections with a thickness of less than 0.1 μm (approximately 80 nm). The thermoplastic resin (Ba), second resin (Bb), and microparticles (the portion after removing reinforcing fibers) of these sections are then observed using a transmission electron microscope. The number-average particle size (Xn) is calculated by randomly selecting more than 400 particles from the obtained image, analyzing the particle size distribution using the Scion Image software manufactured by Scion Corporation, and then substituting the results into the following formula.

[0057] Number-average particle size (Xn) = Σ(Xi×ni) / Σni

[0058] Xi: Particle size

[0059] ni: Number of particles corresponding to particle size (Xi)

[0060] (i=1, 2, 3, ..., n)

[0061] The number-average particle size of the particles formed by the second resin (Bb) is calculated. The number-average particle size can be obtained from an image magnified to 10,000 times. Furthermore, the number-average particle size of the particles contained in the dispersed phase (P2) formed by the second resin (Bb) can be obtained from an image magnified to 35,000 times.

[0062] In this invention, there are no particular limitations on the manufacturing method of the polymer alloy (B), and the following methods are effective for example.

[0063] One method for manufacturing polymer alloy (B) is as follows: A thermoplastic resin (Ba) and a second resin (Bb) having reactive functional groups are fed into a twin-screw extruder with a screw length L to screw diameter D0 ratio L / D0 of 50 or more and multiple fully threaded zones and kneading zones. The maximum resin pressure in the kneading zone of the screw is denoted as Pkmax [MPa], and the minimum resin pressure in the fully threaded zone of the screw is denoted as Pfmin [MPa]. The mixture is then melt-blended to satisfy the condition Pkmax ≥ Pfmin + 0.3.

[0064] The artificial feathers of the present invention may contain other components besides reinforcing fibers (A) and polymer alloys (B) without prejudice to the purpose of the invention. Examples of such other components include: thermosetting resins, inorganic fillers other than carbon fibers, flame retardants, dispersants, nucleating agents, ultraviolet absorbers, antioxidants, shock absorbers, damping agents, antibacterial agents, insect repellents, deodorizing agents, anti-coloring agents, heat stabilizers, release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, defoamers, or coupling agents, etc.

[0065] Secondly, as the molding method for the artificial feathers of the present invention, a molding method using a mold is preferred, and various molding methods such as injection molding, extrusion molding, and pressure molding can be used. In particular, by using an injection molding machine, stable molded products can be obtained continuously. There are no particular provisions for the injection molding conditions, but the following conditions are preferred, for example: injection time: 0.1 seconds to 20 seconds, more preferably 0.2 seconds to 10 seconds; back pressure: 0.1 MPa to 20 MPa, more preferably 3 MPa to 15 MPa; holding pressure: 1 MPa to 150 MPa, more preferably 5 MPa to 140 MPa; holding time: 0.1 seconds to 30 seconds, more preferably 1 second to 20 seconds; cylinder temperature: 180°C to 350°C; mold temperature: 20°C to 160°C. Here, cylinder temperature refers to the temperature of the part of the injection molding machine that heats and melts the molding material, and mold temperature refers to the temperature of the mold into which the resin for forming the specified shape is injected. By appropriately selecting these conditions, especially injection time, back pressure and mold temperature, to satisfy the formula described later [1], the fiber length of the reinforcing fibers in the molded article can be easily adjusted.

[0066] In the artificial feather of the present invention, the weight-average fiber length (LwA1) of the carbon fiber (A1) contained in the reinforcing fiber (A) is 0.5 to 7.0 mm. If the weight-average fiber length (LwA1) is 0.5 mm or more, the mechanical properties of the molded article, especially the bending strength and impact strength, are further improved. Lw is preferably 0.6 mm or more. On the other hand, if the weight-average fiber length (LwA1) is 7 mm or less, the entanglement between the monofilaments of the reinforcing fiber (A) can be suppressed, the dispersion can be further improved, and the fiber breakage caused by the contact between the fibers can be suppressed, thus the mechanical properties of the molded article are further improved. (LwA1) is more preferably 5 mm or less, and even more preferably 4 mm or less. Here, the "weight-average fiber length" in the present invention does not refer to the average value obtained by simply taking the mean value by applying the calculation method of weight-average molecular weight to the calculation of fiber length, but refers to the weight-average fiber length calculated by the following formula considering the contribution of fiber length. However, the following formula is applied when the fiber diameter and density of the reinforcing fiber (A) are constant.

[0067] Weight-average fiber length = Σ(Mi 2 ×Ni) / Σ(Mi×Ni)

[0068] Mi: Fiber length [mm]

[0069] Ni: The number of reinforcing fibers in fiber length Mi.

[0070] The weight-average fiber length can be determined using the following method: Using an optical microscope equipped with a heated stage, a suitable test piece is cut from the molded article. The piece is heated on a heated stage set at 150–350°C, with the material held between glass plates, to achieve a thin film and uniform dispersion, forming a molten state of the polymer alloy (B). This state is observed using an optical microscope (50–200x magnification). The fiber lengths of 1000 randomly selected reinforcing fibers (A) are measured, and the weight-average fiber length (LwA1) is calculated using the above formula. Alternatively, a test piece cut from the molded article is immersed in a solvent capable of dissolving the polymer alloy (B), and appropriate heating is applied to prepare a solution in which the reinforcing fibers (A) are uniformly dispersed. This solution is then filtered, and the reinforcing fibers (A) dispersed on filter paper are observed using an optical microscope (50–200x magnification). The fiber lengths of 1000 randomly selected reinforcing fibers (A) are measured, and the weight-average fiber length (Lw) is calculated using the above formula. In addition, as filter paper used at this time, examples include quantitative filter paper (model: No. 5C) manufactured by ADVANTEC.

[0071] When the molding material used as the artificial feather of the present invention comprises two reinforcing fibers, a material can also be used, for example, by dry blending long fiber particles arranged with the fibers aligned along the long side of the molding material and short fiber particles with the fibers randomly oriented inside the molding material. Regarding the long fiber particles, it is preferable to use long fiber particles manufactured using known techniques, which are in the form of a polymer alloy (B) surrounding the reinforcing fiber (A). Furthermore, short fiber particles can also be produced using known techniques. For example, short fiber particles can be produced by granulating after melt-blending the reinforcing fiber (A) and the polymer alloy (B) using a twin-screw extruder. Here, dry blending differs from melt-blending; it refers to stirring and mixing multiple materials at a temperature where the resin components will not melt, resulting in a substantially homogeneous state. This method is well-suited for use in molding materials that primarily use granular shapes, such as injection molding or extrusion molding.

[0072] If the molding material used to form the feather shaft of the artificial feather of the present invention has a specific gravity of 1.21 or less and an unnotched Charpy impact strength of 75 kJ / m 2 Materials that have a water absorption rate of less than 1.5% when placed in an environment of 80℃×95%RH for 24 hours and have a flexural modulus of more than 5.3GPa when absorbing water at atmospheric equilibrium can achieve stable flight characteristics, especially deceleration performance, and can exhibit high durability without damage even from repeated impacts.

[0073] The feathers used in natural badminton shuttlecocks have a low specific gravity and are extremely lightweight. Furthermore, the rachis of the feather is highly rigid, allowing it to return to its original shape regardless of the number of hits. Therefore, natural badminton shuttlecocks possess a unique flight characteristic of high initial speed followed by deceleration, particularly excellent deceleration performance. On the other hand, if the rigidity of the rachis is increased in artificial badminton shuttlecocks made with synthetic feathers, the weight increases, worsening the weight balance. Therefore, they do not achieve the same flight performance as natural badminton shuttlecocks. Moreover, if the weight of the rachis is reduced, rigidity decreases, and the recovery upon impact slows down. Therefore, flight performance, especially deceleration performance, is reduced.

[0074] If the specific gravity of the molding material used to form the feather shaft of the artificial feather of the present invention exceeds 1.21, the weight balance of the artificial shuttlecock will deteriorate, posing a risk of reduced flight stability, particularly deceleration performance. A specific gravity of 1.20 or less is more preferable. Furthermore, the unnotched Charpy impact strength is less than 75 kJ / m. 2 However, there is a risk of reduced durability due to repeated impacts causing damage to the feather shaft; a more suitable value is 77 kJ / m. 2 The above. Furthermore, when the water absorption rate of artificial feathers exceeds 1.5% and the flexural modulus of elasticity at atmospheric equilibrium is less than 5.3 GPa, the recovery of the feather shaft after bending upon impact is slower, thus posing a risk of reduced flight performance. A water absorption rate of 1.4% or less is more preferable. Furthermore, the flexural modulus of elasticity at atmospheric equilibrium is more preferably 5.5 GPa or more, and even more preferably 5.9 GPa.

[0075] As a method for molding artificial feathers, one can employ: inserting the feather shaft into the mold cavity during mold opening, then closing the mold and injection molding the feather wing portion; or using a two-color molding method, alternatingly molding the feather shaft and wing portion with resins of different materials or colors in a single cycle to create the artificial feather. While insert molding can also be used to integrate the feather shaft and wing portion, two-color molding is preferred from a production efficiency standpoint.

[0076] By using molding materials with the aforementioned properties, it is possible to improve the flight performance of artificial shuttlecocks, especially their deceleration performance, while suppressing damage to the feather shaft.

[0077] The artificial feathers of the present invention, by using the aforementioned molding materials, exhibit high durability and excellent flight performance, especially deceleration performance, and are therefore useful as a substitute for natural badminton feathers.

[0078] Example

[0079] The following embodiments are shown to illustrate the present invention in more detail, but the present invention is not limited to the description of these embodiments. First, the evaluation methods for various properties used in this embodiment will be described.

[0080] (1) Weight-average fiber length

[0081] Test pieces cut from the molded articles were immersed in a solvent capable of dissolving the resin compositions used in the various examples and comparative examples, and subjected to appropriate heat treatment to obtain a solution in which the reinforcing fibers (A) were uniformly dispersed. The solution was then filtered using quantitative filter paper (No. 5C) manufactured by ADVANTEC, and the reinforcing fibers (A) dispersed on the filter paper were observed using an optical microscope (50–200x). The fiber lengths of 1000 randomly selected reinforcing fibers (A) were measured, and the weight-average fiber length (LwA1) was calculated using the following formula.

[0082] Average fiber length = Σ(Mi 2 ×Ni) / Σ(Mi×Ni)

[0083] Mi: Fiber length [mm]

[0084] Ni: Number of fibers in fiber length Mi

[0085] (2) Determination of the bending strength and flexural modulus of the molded product, and the flexural modulus when absorbing water.

[0086] For the ISO-type dumbbell test pieces obtained through the various embodiments and comparative examples, according to ISO 178:2010, Amd.1:2013, a 3-point bending test fixture (indenter radius 5 mm) was used, with the fulcrum distance set to 64 mm, and the test conditions at a test speed of 2 mm / min to determine the bending strength and flexural modulus. An Instron universal testing machine model 5566 (manufactured by Instron Corporation) was used as the testing machine. The tests were performed three times, and the average value was calculated as the bending strength and flexural modulus for each embodiment and comparative example. The flexural modulus was calculated from the stress gradient within a specified strain range (0.05–0.25%). Furthermore, the flexural modulus of the water-absorbing ISO-type dumbbell test pieces described later were also determined in the same manner as above.

[0087] (3) Charpy impact strength test of molded articles

[0088] The parallel portion of the ISO-type dumbbell test piece obtained through the various embodiments and comparative examples was cut out. An unnotched Charpy impact test was performed using a Tokyo Testing Machine Co., Ltd. C1-4-01 type testing machine according to ISO 179, and the impact strength [kJ / cm²] was calculated. 2 ].

[0089] (4) Morphological observation

[0090] JIS-5A dumbbell-shaped or bending test pieces obtained by injection molding were cut into 1-2 mm square sections along their cross-section. These sections were then stained with ruthenium tetroxide, and the second resin (Bb) containing reactive functional groups was stained as well. The test pieces were then cut at -196°C using an ultramicrotome to obtain ultrathin sections with a thickness of less than 0.1 μm (approximately 80 nm). These sections were observed using a transmission electron microscope. The number-average particle size (Xn) was calculated by randomly selecting more than 400 particles from the obtained image, analyzing the particle size distribution using Scion Corporation's "Scion Image" image analysis software, and then substituting the results into the following formula.

[0091] Number-average particle size (Xn) = Σ(Xi×ni) / Σni

[0092] Xi: Particle size

[0093] ni: Number of particles corresponding to particle size (Xi)

[0094] (i=1, 2, 3, ..., n)

[0095] The number-average particle size of the particles formed by the second resin (Bb) was calculated from an image magnified to 10,000 times, and the number-average particle size of the microparticles contained in the second resin (Bb) was calculated from an image magnified to 35,000 times. The presence or absence of microparticles with a number-average particle size of 1–100 nm contained in the second resin (Bb) was confirmed.

[0096] (5) Water absorption rate determination

[0097] The ISO-type dumbbell test pieces obtained through the various examples and comparative examples were placed in a constant temperature room at 23°C and 50% humidity for 24 hours and then weighed. They were then placed in an environment at 80°C and 95% RH for 24 hours. Afterward, the weight of the obtained water-absorbing ISO-type dumbbell test pieces was measured after wiping off the moisture, and the water absorption rate of the ISO-type dumbbell test pieces before and after water absorption was calculated.

[0098] (6) Evaluation of the deceleration performance of artificial shuttlecocks

[0099] The flight speed of the artificial shuttlecocks obtained in each embodiment was measured by striking them with racket strings strung on a carbon racket rotating at 230 km / h. The artificial shuttlecocks, flying in a straight line after being struck, were filmed using a high-speed camera at a frame rate of 5000 fps, and the average speed of the artificial shuttlecocks (average speed over a distance of 10 m from the striking point) was calculated using the following formula. The average speed was calculated using a sample size of N=3, and evaluated using the following criteria.

[0100] Average speed over 10 meters (km / h) = 0.01km ÷ arrival time at 10 meters (h)

[0101] Final speed less than 90km / h: 0 (Pass)

[0102] Final speed of 90km / h or higher: × (Fail)

[0103] (7) Durability evaluation of artificial shuttlecocks

[0104] Regarding the durability of the artificial shuttlecocks obtained from each embodiment, after curing for 12 hours in an environment of 5°C and 30% humidity, they were hit under the same conditions using racket strings threaded on a carbon racket rotating at a speed of 230 km / h. The following benchmarks were used to evaluate the number of hits until the axle broke, and Δ and 0 were defined as acceptable.

[0105] The shaft broke after more than 50 impacts without sustaining damage: ○ (Excellent)

[0106] The shaft broke after more than 45 impacts, but no damage occurred: △ (Good)

[0107] The shaft breaks after fewer than 45 impacts, indicating damage: × (Unacceptable)

[0108] (Refer to Example 1)

[0109] [Production of carbon fiber (A1)]

[0110] A copolymer with polyacrylonitrile as the main component is spun, sintered, and surface oxidized to obtain a fiber with a total of 24,000 monofilaments, a single fiber diameter of 7 μm, a mass of 1.6 g / m per unit length, and a specific gravity of 1.8 g / cm³. 3 Continuous carbon fibers with a surface oxygen concentration ratio (O / C) of 0.2 were obtained. The tensile strength of these continuous carbon fibers was 4,880 MPa, and the tensile modulus of elasticity was 225 GPa. Next, a sizing agent stock solution was prepared by dissolving glycerol polyglycidyl ether, a multifunctional compound, in water at a concentration of 2% by weight. The carbon fibers were then coated with the sizing agent by impregnation and dried at 230°C. The carbon fibers obtained as described above had a sizing agent adhesion amount of 1.0% by weight.

[0111] [Glass fiber (A2)]

[0112] It uses glass fiber "T-249" (manufactured by Nippon Electric Glass Co., Ltd.).

[0113] [Thermoplastic resin (Ba)]

[0114] (Ba-1)

[0115] The polyamide resin (Toray Co., Ltd., Nylon 610 resin "AMILAN" (registered trademark) CM2001) is used.

[0116] [Second resin (Bb) with reactive functional groups]

[0117] (Bb-1)

[0118] The maleic anhydride-modified ethylene-1-butene copolymer “TAFMER” (registered trademark) MH7020 (manufactured by Mitsui Chemicals Co., Ltd.) is used.

[0119] (Example 1)

[0120] A long fiber reinforced resin pellet manufacturing apparatus, equipped with a coating die for wire coating, is installed at the front end of a TEX-30α twin-screw extruder (screw diameter 30 mm, L / D=32) manufactured by Nippon Steel Co., Ltd. The extruder barrel temperature is set to 260°C. A resin composition containing at least the aforementioned thermoplastic resin (Ba-1) and second resin (Bb) is fed from the main hopper and melt-blended. Molten thermoplastic resin is continuously prepared to coat the carbon fibers (A1). After cooling the resulting strands, they are cut into pellets with a length of 7 mm to produce long fiber pellets (A1-1). At this time, the drawing speed is adjusted so that the carbon fibers (A1-1) are 30 parts by weight relative to a total of 100 parts by weight of the reinforcing fiber (A) and the resin composition. The length of the carbon fibers (A1) and the pellet length of the resulting long fiber pellets (A1-1) are substantially the same.

[0121] On the other hand, glass fiber (A2) and a resin composition comprising at least the aforementioned thermoplastic resin (Ba-1) and second resin (Bb) are extruded using a co-rotating, fully meshing twin-screw extruder (manufactured by Nippon Steel Works Co., Ltd., TEX-65αII) with two screws having a screw diameter of 65 mm and a double-threaded screw, and an L / D ratio of 35. The screw configuration at this time is as follows: three kneading zones are provided starting from positions L / D=7, 16, and 25, with the lengths Lk / D of each kneading zone set sequentially to Lk / D=3.0, 3.0, and 3.0. Furthermore, a reverse screw zone is provided downstream of each kneading zone, with the lengths Lr / D of each reverse screw zone set sequentially to Lr / D=0.5, 0.5, and 0.5. A vacuum zone at the exhaust port is set at L / D=30 to remove volatile components at a gauge pressure of -0.1 MPa. Molten resin from a 4mm φ×23 hole is drawn into strands through a die and cooled in a cooling bath. The strands are then simultaneously drawn and cut using a granulator to obtain glass short fiber granules (A2-1). These granules are vacuum dried at 80°C for at least 12 hours and then dry-blended with the aforementioned long fiber granules in the proportions shown in Table 1. Injection molding is then performed using an injection molding machine (J110AD, Nippon Steel Works Co., Ltd.) under the following conditions: injection time: 2 seconds, back pressure: 5 MPa, holding pressure: 40 MPa, holding time: 10 seconds, cylinder temperature: 260°C, and mold temperature: 60°C. This produces ISO-type dumbbell test pieces as molded products. Here, cylinder temperature refers to the temperature of the part of the injection molding machine that heats and melts the molding material, and mold temperature refers to the temperature of the mold into which the resin is injected to form the specified shape. The resulting test pieces (molded products) are left to stand in a constant temperature and humidity chamber at 23°C and 50%RH for 24 hours before being supplied for characteristic evaluation. The evaluation results obtained by the aforementioned methods are summarized in Table 1.

[0122] In addition, the following method was used to produce the product according to the proportions shown in Table 1. Figure 1 The artificial feather 1 shown (feather shaft 1a and feather wing 1b) and Figure 2 The artificial shuttlecock 11 shown is used to perform the aforementioned shuttlecock deceleration performance evaluation and durability evaluation.

[0123] [How to make artificial feathers]

[0124] The artificial feather 1 is formed using a two-color molding method with two injection molding machines (Injection Molding Machine I and Injection Molding Machine II). First, using Injection Molding Machine II, resin particles containing the feather shaft portion 1a formed by Injection Molding Machine I are injected into a mold under the following conditions: injection time 0.2 seconds, back pressure 3 MPa, holding pressure 65 MPa, holding time 0.2 seconds, cylinder temperature 215°C, and mold temperature 60°C, thereby forming the feather wing portion 1b. Next, long fiber particles (A1-1) and short glass fiber particles (A2-1) are mixed together and injection molded using Injection Molding Machine I under the following conditions: injection time 0.2 seconds, back pressure 7 MPa, holding pressure 130 MPa, holding time 1.8 seconds, cylinder temperature 285°C, and mold temperature 60°C, thereby forming the feather shaft portion 1a and producing the artificial feather 1.

[0125] [How to Make Artificial Shuttlecocks]

[0126] The feather shafts 1a of multiple artificial feathers 1, produced by the above method, are embedded in a ring around the circumference of the flat surface of a base portion 2, which is formed by covering a cork platform with a thin skin. The base portion 2 is hemispherical in shape with a diameter of 25 mm to 28 mm and has a flat surface. Furthermore, the multiple artificial feathers 1 are arranged such that the spacing between them increases as they move away from the base portion 2, and each artificial feather 1 is arranged to overlap with its adjacent artificial feather 1. In this way, a skirt 4 is formed by the multiple artificial feathers 1 and they are fixed together with rope-like members 3, thereby creating an artificial badminton shuttlecock 11.

[0127] (Examples 2-4, Comparative Examples 1 and 3)

[0128] The composition ratios were changed to those shown in Table 1, and the process was otherwise the same as in Example 1. ISO test pieces and artificial shuttlecocks were prepared and evaluated. The evaluation results are summarized in Table 1.

[0129] (Comparative Example 2)

[0130] Carbon fiber (A1) bundles and thermoplastic resin (Ba-1) as described above were fed into the main hopper of a TEX-30α twin-screw extruder (screw diameter 30 mm, L / D=32) manufactured by Nippon Steel Works Co., Ltd. The screw rotation speed was set to 200 rpm, and the mixture was melt-blended in the cylinder. The molten resin, extruded from a 4 mm φ×23 orifice, was drawn into strands through a die and cooled in a cooling bath. The strands were then simultaneously drawn and cut through a granulator to obtain carbon short fiber granules (A2-1). These granules were vacuum-dried at 80°C for at least 12 hours and then dry-blended with the aforementioned glass short fiber granules (A2-1) in the proportions shown in Table 1. Otherwise, the process was the same as in Example 1 to produce ISO test pieces and artificial badminton shuttlecocks, and the results were evaluated. The evaluation results are summarized in Table 1.

[0131] Example 1 demonstrated high impact strength and excellent flexural modulus of elasticity when absorbing water as the molding material. As a result, the artificial shuttlecock completed more than 50 hit tests in terms of durability, and the average speed from the point of impact to the point of reaching 10m was less than 88km / h, demonstrating excellent deceleration performance. Furthermore, Examples 2-4, with varying contents of carbon fiber (A1) and glass fiber (A2), also exhibited high impact strength and excellent flexural modulus of elasticity when absorbing water, resulting in excellent flight performance of the artificial shuttlecock.

[0132] On the other hand, Comparative Example 1 does not contain carbon fiber (A1), resulting in weak fiber reinforcement and insufficient flexural modulus of elasticity when the molding material absorbs water. Consequently, the artificial shuttlecock exhibits high deceleration performance, i.e., a high average speed at 10m. Furthermore, Comparative Example 2 uses short carbon fiber particles (A1-2), resulting in a shorter weight-average fiber length (LwA1) in the molded product and low unnotched Charpy impact strength, leading to reduced durability of the artificial shuttlecock. Moreover, Comparative Example 3 does not contain resin with reactive functional groups (Bb-1), resulting in reduced toughness as the molding material, poor impact strength of the molded product, and reduced durability of the artificial shuttlecock.

[0133]

[0134] Industry availability

[0135] The artificial feathers for badminton shuttlecocks of the present invention have excellent durability, flight performance, and especially deceleration performance, and therefore can be well used as a component to replace the feather shaft of natural badminton shuttlecocks.

[0136] Explanation of reference numerals in the attached figures

[0137] 1: Artificial feathers

[0138] 1a: Feather shaft

[0139] 1b: Feathered wings

[0140] 2: Base section

[0141] 3: Rope-like components

[0142] 4: Skirt

[0143] 11: Artificial shuttlecock

Claims

1. An artificial feather for badminton, comprising a feather shaft and feather wings supported by the feather shaft, the feather shaft being made of reinforcing fiber A containing at least carbon fiber A1 and a polymer alloy B, the artificial feather being inserted in a ring shape into the base of the badminton shuttlecock. Relative to a total of 100 parts by weight of reinforcing fiber A and polymer alloy B, the artificial feather for badminton shuttlecock comprises 1 to 50 parts by weight of reinforcing fiber A containing at least carbon fiber, and 50 to 99 parts by weight of polymer alloy B, wherein the weight-average fiber length LwA1 of carbon fiber A1 is 0.5 to 7.0 mm.

2. The artificial feather for badminton as described in claim 1, wherein the polymer alloy B comprises a continuous phase P1 and a dispersed phase P2, wherein the dispersed phase P2 is dispersed in the continuous phase P1 in a particulate form with a dispersion diameter of 10 to 1000 nm.

3. The artificial feather for badminton as described in claim 1 or 2, wherein the dispersed phase P2 contains microparticles with a particle size of 1 to 100 nm.

4. The artificial feather for badminton as described in claim 1 or 2, wherein the feather shaft is made of a molding material. The specific gravity of the molding material is below 1.21, and the unnotched Charpy impact strength is 75 kJ / m. 2 The water absorption rate after being placed in an environment of 80℃×95%RH for 24 hours is less than 1.5%, and the flexural modulus of elasticity when absorbing water at atmospheric equilibrium is greater than 5.3GPa.

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