Artificial feather for shuttlecock

Abstract

Provided is an artificial feather for a shuttlecock comprising: a feather shaft part composed of a reinforcing fiber (A) including at least a carbon fiber (A1) and a polymer alloy (B); and a feather wing part supported by the feather shaft part, the artificial feather being annularly implanted in a base part of the shuttlecock. The artificial feather for a shuttlecock includes, with respect to 100 parts by weight of the total of the reinforcing fibers (A) and (B), 1-50 parts by weight of the reinforcing fiber (A) containing at least carbon fibers, and 50-99 parts by weight of the polymer alloy (B), wherein the weight average fiber length (LwA1) of the carbon fiber (A1) is 0.5-7.0 mm. Also provided is an artificial shuttlecock having excellent impact strength and flexural modulus upon water absorption.

Description

Artificial shuttlecock feathers

[0001] The present invention relates to an artificial feather for use in a shuttlecock used in badminton.

[0002] Compositions containing reinforcing fibers and thermoplastic resins are lightweight and have excellent mechanical properties, and are therefore widely used in sporting goods, aerospace, and general industrial applications. These reinforcing fibers include metal fibers such as aluminum fibers and stainless steel fibers, inorganic fibers such as silicon carbide fibers and carbon fibers, and organic fibers such as aramid fibers and polyparaphenylenebenzoxazole (PBO) fibers. Carbon fibers are preferred from the standpoint of the balance between specific strength, specific rigidity, and light weight, and polyacrylonitrile (PAN)-based carbon fibers are particularly preferred. Reinforcing fibers, when combined with thermoplastic resins, have excellent reinforcing effects.

[0003] Badminton shuttlecocks are classified into two types: those that use waterfowl feathers (natural feathers) for the feathers (natural shuttlecocks), and those that use artificial feathers made from nylon resin or the like (artificial shuttlecocks).

[0004] As is well known, a natural feather shuttlecock is made using around 16 natural feathers from a goose, duck, or other bird, with the end of each feather's rachis attached to a hemispherical base made of cork or other material covered with leather. The feathers used in natural feather shuttlecocks have a low specific gravity and are extremely lightweight. In addition, the feather rachis has high rigidity. This gives natural feather shuttlecocks unique flight performance and a comfortable feel when hitting the ball.

[0005] However, the feathers used as the raw material for natural shuttlecocks are collected from the above-mentioned waterfowl, and not all parts of the waterfowl are suitable for use in shuttlecocks. As a result, only a small amount of feathers can be collected from a single waterfowl for use in shuttlecocks, making the supply unstable. There is also variation in performance.

[0006] On the other hand, a well-known artificial shuttlecock is one that has resin feathers that are molded into a ring shape as one piece, but because the feathers of this artificial shuttlecock do not move independently like those of a natural shuttlecock, it is difficult to obtain the same flight performance as a natural shuttlecock.

[0007] Therefore, as described in the following patent documents, artificial feathers that imitate feathers have been proposed, namely, artificial shuttlecocks have been proposed that have artificial feathers that include a feather portion and a feather shaft portion that supports the feather portion.

[0008] One method for improving the durability and flight performance of an artificial shuttlecock is to use a fiber-reinforced thermoplastic resin (see, for example, Patent Document 1). Furthermore, a method for using a carbon fiber-reinforced thermoplastic resin for the inside of the artificial shuttlecock has been proposed as a means for increasing the rigidity and lightness of the artificial shuttlecock (see, for example, Patent Document 2). Furthermore, a resin in which a resin having a reactive functional group has been added to the thermoplastic resin has been proposed as a means for improving the impact resistance of a fiber-reinforced thermoplastic resin (see, for example, Patent Documents 3 and 4).

[0009] However, the artificial shuttlecocks obtained using these techniques and the fiber-reinforced thermoplastic resins used in them lack the durability and deceleration performance required for artificial shuttlecocks, and there have been issues with the impact strength as a material and the flexural modulus when absorbing water being insufficient.

[0010] As described above, with conventional technology, it has not been possible to obtain an artificial shuttlecock made of fiber-reinforced thermoplastic resin with a thermoplastic resin matrix that has high impact properties and a flexural modulus when absorbing water, and there has been a demand for the development of such a fiber-reinforced thermoplastic resin composition.

[0011] JP 2017-202001 A JP 2012-75867 A International Publication No. 2013 / 015111 International Publication No. 2010 / 107022

[0012] In view of the above-mentioned problems with the prior art, the present invention has an object to provide an artificial leather shuttlecock that is excellent in impact strength and flexural modulus when absorbing water.

[0013] In order to solve the above problems, the present invention is mainly composed of the following: (1) An artificial shuttlecock feather that is implanted in a circular pattern in the base section of a shuttlecock, the artificial shuttlecock feather comprising: a feather shank portion made of reinforcing fiber (A) containing at least carbon fiber (A1) and a polymer alloy (B); and a feather aerofoil portion supported by the feather shank portion, the artificial shuttlecock feather comprising 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) per 100 parts by weight total of reinforcing fiber (A) and polymer alloy (B), the carbon fiber (A1) having a weight average fiber length (LwA1) of 0.5 to 7.0 mm. (2) The artificial shuttlecock feather according to (1), wherein the polymer alloy (B) is made of a continuous phase (P1) and a dispersed phase (P2), the dispersed phase (P2) being dispersed in the continuous phase (P1) in the form of particles with a dispersion diameter of 10 to 1,000 nm. (3) The artificial shuttlecock feather according to (1) or (2), wherein the dispersed phase (P2) contains fine particles having a particle diameter of 1 to 100 nm. (4) The artificial shuttlecock feather according to (1) or (2), wherein the feather shaft portion has a specific gravity of 1.21 or less and an unnotched Charpy impact strength of 75 kJ / m ２ or more, and which is made of a molding material that has a water absorption rate of 1.5% or less when left to stand for 24 hours in an environment of 80°C x 95% RH, and a flexural modulus of elasticity at atmospheric equilibrium water absorption of 5.3 GPa or more.

[0014] The artificial feather for an artificial shuttlecock of the present invention comprises reinforcing fibers and a polymer alloy, and because the reinforcing fibers are long, the reinforcing effect of the reinforcing fibers is high, making it possible to obtain an artificial shuttlecock that has excellent impact strength and flexural modulus when water is absorbed.

[0015] 1 is a schematic configuration diagram showing an artificial feather for a shuttlecock according to one embodiment of the present invention. 2 is a schematic perspective view showing one embodiment of an artificial shuttlecock using the artificial feather of the present invention.

[0016] DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to embodiments. The artificial shuttlecock feather of the present invention is made of reinforcing fibers (A) containing at least carbon fibers and a polymer alloy (B).

[0017] The reinforcing fibers (A) are preferably in the form of continuous reinforcing fiber bundles as a starting material, and as a reinforcing material, they impart high mechanical properties to the molded article. The polymer alloy (B) is a matrix resin with high physical properties such as toughness, and plays a role in firmly holding the reinforcing fibers (A).

[0018] The type of fiber contained in the reinforcing fiber (A) is not particularly limited as long as it contains at least carbon fiber, but it is preferable that it further contains glass fiber as a fiber with a high reinforcing effect. Depending on the target reinforcing effect, it is preferable to use two or more types of these reinforcing fibers in combination.

[0019] The content of the reinforcing fiber (A) in the composition of the artificial feather is preferably 1 to 50 parts by weight of the reinforcing fiber (A) containing at least carbon fiber per 100 parts by weight of the total of the reinforcing fiber (A) and the polymer alloy (B).

[0020] If the reinforcing fiber content is less than 1 part by weight, the durability of the artificial shuttlecock will decrease. The reinforcing fiber content 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, if the reinforcing fiber content exceeds 50 parts by weight, entanglement of the fibers will increase, the dispersion of the reinforcing fibers in the molded product will decrease, and fiber breakage will increase, causing the fibers to become shorter, which often leads to a decrease in the deceleration performance of the artificial shuttlecock. The reinforcing fiber content 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.

[0021] The artificial feather composition contains a polymer alloy (B). The polymer alloy (B) of the present invention is preferably composed of at least two different thermoplastic resins (Ba) and a second resin (Bb) having a reactive functional group.

[0022] It is preferable that the polymer alloy (B) contains a thermoplastic resin (Ba) and a second resin (Bb), because this increases the impact strength and flexural modulus of elasticity of the artificial shuttlecock when absorbing water. There are no particular restrictions on the types of thermoplastic resin (Ba) and second resin (Bb) contained in the polymer alloy (B). However, it is preferable to use the type of thermoplastic resin described below as a thermoplastic resin with excellent mechanical strength as the thermoplastic resin (Ba), and it is preferable to use the type of thermoplastic resin described below as a thermoplastic resin with particularly excellent impact strength as the second resin (Bb) having a reactive functional group. Depending on the desired effect, it is also preferable to use two or more of these thermoplastic resins in combination. In this case, the combination of thermoplastic resins is appropriately selected depending on the desired properties.

[0023] <Thermoplastic Resin (Ba)> The thermoplastic resin (Ba) preferably has a molding temperature (melting temperature) of 200 to 450°C, and examples thereof include polyolefin resins, polystyrene resins, polyamide resins, halogenated vinyl resins, polyacetal resins, 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 correspond to electrical insulators. Two or more of these may also be used. Among these, polyamide resins are preferred from the viewpoints of moldability, mechanical properties, and light weight.

[0024] Here, the polyamide resin is a resin whose main raw materials are amino acids, lactams, or diamines and dicarboxylic acids. Typical examples of the main raw materials include amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and para-aminomethylbenzoic acid, lactams such as ε-caprolactam and ω-laurolactam, aliphatic diamines such as tetramethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, and 5-methylnonamethylenediamine, aromatic diamines such as metaxylylenediamine and paraxylylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, and 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane. Alicyclic diamines such as hexane, bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, 2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine, and aminoethylpiperazine; aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodiumsulfoisophthalic acid, 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 may be used.

[0025] As the thermoplastic resin (Ba), a polyamide resin having a melting point of 200° C. or higher is particularly useful because of its excellent mechanical properties. Specific examples thereof include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polycaproamide / polyhexamethylene adipamide copolymer (nylon 6 / 66), polytetramethylene adipamide (nylon 46), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polydecamethylene decamide (nylon 1010), polydecamethylene dodecamide (nylon 1012), polydodecamethylene dodecamide (nylon 1212), polyundecaneamide (nylon 11), polydodecanamide (nylon 12), polyhexamethylene terephthalamide / polycaproamide copolymer (nylon 6T / 6), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 6T / 6), Examples of such a copolymer include polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / polydodecanamide copolymer (nylon 6T / 12), polyhexamethylene terephthalamide / poly(2-methylpentamethylene) terephthalamide copolymer (nylon 6T / M5T), polyxylylene adipamide (nylon XD6), polynonamethylene terephthalamide (nylon 9T), and copolymers thereof. Two or more of these may be used. Among these, nylon 6, nylon 66, nylon 610, nylon 11, nylon 12 and nylon 9T are more preferred.

[0026] There are no particular restrictions on the degree of polymerization of these polyamide resins, and the relative viscosity of a solution obtained by dissolving 0.25 g of polyamide resin in 25 ml of 98% concentrated sulfuric acid, measured at 25°C, is preferably in the range of 1.5 to 5.0, and more preferably in the range of 2.0 to 3.5.

[0027] <Second Resin (Bb) Having a Reactive Functional Group> The base resin for the second resin (Bb) having a reactive functional group is not particularly limited, but may be at least one resin selected from, for example, polyamide, polyester, polyphenylene sulfide, polyphenylene oxide, polycarbonate, polylactic acid, polyacetal, polysulfone, tetrafluoroethylene, polyetherimide, polyamideimide, polyimide, polyethersulfone, polyetherketone, polythioetherketone, polyetheretherketone, polyethylene, polypropylene, styrene-based resins such as polystyrene and ABS, rubber polymers, polyalkylene oxides, etc., and is different from the polyamide resin (Ba). Among these, as the base resin for the second resin (Bb), resins selected from polyolefin resins such as polyethylene resins and polypropylene resins, styrene-based resins, and rubber polymers are more preferred due to the ease of introducing reactive functional groups, and rubber polymers are even more preferred from the viewpoint of imparting impact absorption properties.

[0028] The rubbery polymer is a polymer containing a polymer with a low glass transition temperature, in which some of the intermolecular bonds are constrained by covalent bonds, ionic bonds, van der Waals forces, entanglement, etc. The glass transition temperature of the rubbery polymer is preferably 25° C. or lower. If the glass transition temperature exceeds 25° C., there is a risk of poor impact resistance.

[0029] Examples of rubbery polymers include diene rubbers such as polybutadiene, polyisoprene, random copolymers and block copolymers of styrene-butadiene, hydrogenated products of these block copolymers, 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 and α-olefins; ethylene-unsaturated carboxylic acid copolymers such as ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers; ethylene-unsaturated carboxylic acid ester copolymers such as ethylene-acrylic acid esters and ethylene-methacrylic acid esters; copolymers in which a part of the unsaturated carboxylic acid is gold; Preferred examples of the polymerizable monomer include metal salts such as ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid metal salt copolymers, such as ethylene-acrylic acid-metal acrylic acid salt and ethylene-methacrylic acid-metal methacrylic acid salt; acrylic acid ester-butadiene copolymers, acrylic elastic polymers, such as butyl acrylate-butadiene copolymer; copolymers of ethylene and fatty acid vinyl, such as ethylene-vinyl acetate; ethylene-propylene non-conjugated diene terpolymers, such as ethylene-propylene-ethylidenenorbornene copolymer and ethylene-propylene-hexadiene copolymer; butylene-isoprene copolymer; chlorinated polyethylene; and thermoplastic elastomers, such as polyamide elastomers and polyester elastomers.

[0030] When used for the thermoplastic resin (Ba), from the viewpoint of obtaining excellent impact strength, an ethylene-unsaturated carboxylic acid ester copolymer, an ethylene-propylene random copolymer or block copolymer, an ethylene-butene random copolymer or block copolymer, or a copolymer of ethylene and an α-olefin is preferably used.

[0031] The unsaturated carboxylic acid ester in the ethylene-unsaturated carboxylic acid ester copolymer is preferably a (meth)acrylic acid ester. Specific examples of unsaturated carboxylic acid esters include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and stearyl (meth)acrylate. Here, "(meth)acrylic acid" means "acrylic acid or methacrylic acid." The weight ratio of the ethylene component to the unsaturated carboxylic acid ester component in the copolymer is not particularly limited, but is preferably in the range of 90 / 10 to 10 / 90, more preferably 85 / 15 to 15 / 85. The number-average molecular weight of the ethylene-unsaturated carboxylic acid ester copolymer is not particularly limited, but is preferably in the range of 1,000 to 70,000 from the viewpoints of fluidity and mechanical properties.

[0032] The reactive functional group contained in the second resin (Bb) having a reactive functional group is not particularly limited as long as it reacts with the functional group present in the thermoplastic resin (Ba), but preferably includes at least one selected from an amino group, a carboxyl group, a metal salt of a carboxyl group, a hydroxyl group, an epoxy group, an acid anhydride group, an isocyanate group, a mercapto group, an oxazoline group, a sulfonic acid group, etc. Among these, groups selected from an amino group, a carboxyl group, a metal salt of a carboxyl group, an epoxy group, an acid anhydride group, and an oxazoline group are more preferably used because they have high reactivity and are less likely to undergo side reactions such as decomposition and crosslinking.

[0033] When an acid anhydride group is introduced into a rubbery polymer, the method can be carried out by a known technique and is not particularly limited. For example, a method of copolymerizing an acid anhydride such as maleic anhydride, itaconic anhydride, endic anhydride, citraconic anhydride, or 1-butene-3,4-dicarboxylic anhydride with a monomer that is a raw material for the rubbery polymer, or a method of grafting an acid anhydride onto a rubbery polymer can be used.

[0034] The number of functional groups per molecular chain in the second resin (Bb) having reactive functional groups is not particularly limited, but is usually preferably 1 to 10, and more preferably 1 to 5 in order to reduce side reactions such as crosslinking.

[0035] The polymer alloy (B) is composed of a thermoplastic resin (Ba) and a second resin (Bb) having a reactive functional group. The polymer alloy (B) can be obtained by melt-kneading the thermoplastic resin (Ba) and the second resin (Bb) having a reactive functional group. By using the second resin (Bb) having a reactive functional group, the polymer alloy (B) contains a continuous phase (P1) and a dispersed phase (P2) during melt-kneading of the thermoplastic resin (Ba) and the second resin (Bb), and even after completion of melt-kneading, some of the reactive functional groups remain in the second resin (Bb) while retaining their reactivity. This allows for highly controlled particle structure of the second resin (Bb), which greatly contributes to improved impact resistance.

[0036] The dispersed phase (P2) is preferably dispersed in the form of particles having a size of 10 to 1,000 nm. If the number average particle size of the particles is less than 10 nm, the impact resistance that is a feature of the present invention will not be exhibited, and if it exceeds 1,000 nm, there is a risk that the rigidity that is a feature of the present invention will decrease. By including particles made of the second resin (Bb) whose structure is highly controlled, an artificial feather composition that has an excellent balance between rigidity and impact resistance can be obtained, and the durability and deceleration performance of the artificial feather shuttlecock used therewith can be improved.

[0037] Furthermore, the artificial feather shuttlecock of the present invention preferably contains fine particles with a particle size of 1 to 100 nm within the dispersed phase (P2). By controlling the structure within the dispersed phase as described above, it is possible to obtain an artificial feather composition with an even better balance between rigidity and impact resistance, and an artificial feather shuttlecock using the same.

[0038] Note that known techniques can be applied to the morphology observation method. For example, the cross-sectional center of the test piece is cut into 1-2 mm squares, the second resin (Bb) having a reactive functional group is stained with ruthenium tetroxide, and then ultrathin sections of 0.1 μm or less (approximately 80 nm) in thickness are obtained using an ultramicrotome. The thermoplastic resin (Ba), second resin (Bb), and fine particle portion (excluding the reinforcing fibers) of the section are observed using a transmission electron microscope. The number average particle size (Xn) of the particles is determined by randomly extracting 400 or more particles from the obtained image, analyzing the particle size distribution using Scion Corporation's image analysis software "Scion Image," and using the following formula: Number average particle size (Xn) = Σ(Xi × ni) / Σni Xi: particle size ni: number of particles corresponding to particle size (Xi) (i = 1, 2, 3, ..., n)

[0039] The particle diameter of the particles made of the second resin (Bb) is determined by the number average. The number average particle diameter can be determined from an image magnified 10,000 times. Furthermore, the number average particle diameter of the fine particles contained in the dispersed phase (P2) made of the second resin (Bb) can be determined from an image magnified 35,000 times.

[0040] In the present invention, the method for producing the polymer alloy (B) is not particularly limited, but the following method is effective, for example.

[0041] One method for producing the polymer alloy (B) is to feed a thermoplastic resin (Ba) and a second resin (Bb) having a reactive functional group into a twin-screw extruder having a screw length L to screw diameter D0 ratio L / D0 of 50 or more and a plurality of full-flight zones and kneading zones, and melt-kneading the resin under conditions where Pkmax [MPa] is the maximum resin pressure among the resin pressures in the kneading zones in the screw, and Pfmin [MPa] is the minimum resin pressure among the resin pressures in the full-flight zones in the screw. Pkmax ≧ Pfmin + 0.3 is satisfied.

[0042] The artificial feather of the present invention may contain other components in addition to the reinforcing fiber (A) and the polymer alloy (B), provided that the object of the present invention is not impaired. Examples of such other components include thermosetting resins, inorganic fillers other than carbon fiber, flame retardants, dispersants, crystal nucleating agents, ultraviolet absorbers, antioxidants, impact absorbers, vibration dampers, antibacterial agents, insect repellents, deodorizers, coloring inhibitors, heat stabilizers, release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, and coupling agents.

[0043] Next, the method for molding the artificial feathers of the present invention is preferably a molding method using a mold, and various molding methods such as injection molding, extrusion molding, and press molding can be used. In particular, molding methods using an injection molding machine enable continuous, stable molded products to be obtained. There are no particular restrictions on the injection molding conditions, but preferred conditions include an injection time of 0.1 to 20 seconds, more preferably 0.2 to 10 seconds; a back pressure of 0.1 to 20 MPa, more preferably 3 to 15 MPa; a dwell pressure of 1 to 150 MPa, more preferably 5 to 140 MPa; a dwell time of 0.1 to 30 seconds, more preferably 1 to 20 seconds; a cylinder temperature of 180°C to 350°C; and a mold temperature of 20°C to 160°C. Here, the cylinder temperature refers to the temperature of the part of the injection molding machine where the molding material is heated and melted, and the mold temperature refers to the temperature of the mold into which the resin is injected to form the desired shape. By appropriately selecting these conditions, particularly the injection time, back pressure, and mold temperature, the fiber length of the reinforcing fibers in the molded product can be easily adjusted so as to satisfy the formula [1] described below.

[0044] 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. A weight-average fiber length (LwA1) of 0.5 mm or more further improves the mechanical properties of the molded article, particularly bending strength and impact resistance. Lw is preferably 0.6 mm or more. On the other hand, a weight-average fiber length (LwA1) of 7 mm or less suppresses entanglement between the single filaments of the reinforcing fiber (A), further improving dispersion and further suppressing fiber breakage due to contact between the fibers, thereby further improving the mechanical properties of the molded article. (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 refers to the weight-average fiber length calculated using the following formula, which takes into account the contribution of fiber length, rather than simply taking a number average, by applying the method for calculating the weight-average molecular weight to calculate the fiber length. However, the following formula applies when the fiber diameter and density of the reinforcing fiber (A) are constant. Weight average fiber length = Σ (Mi ２ × Ni) / Σ(Mi × Ni) Mi: fiber length [mm] Ni: number of reinforcing fibers of fiber length Mi

[0045] The weight-average fiber length can be measured by the following method. Using an optical microscope with a hot stage, an appropriate test piece is cut out from the molded product, and the test piece is heated while sandwiched between glass plates on a hot stage appropriately set at 150 to 350 ° C., matching the melting temperature of the polymer alloy (B) used. The test piece is then uniformly dispersed in a film-like form, and the polymer alloy (B) is observed with an optical microscope (50 to 200 magnification) in a molten state. The fiber lengths of 1,000 randomly selected reinforcing fibers (A) are measured, and the weight-average fiber length (LwA1) is calculated from the above formula. Alternatively, a test piece cut out from the molded product is placed in a solvent in which the polymer alloy (B) dissolves, and appropriately heated to prepare a solution in which the reinforcing fibers (A) are uniformly dispersed. The solution is then filtered, and the reinforcing fibers (A) dispersed on filter paper are observed with an optical microscope (50 to 200 magnification). The fiber lengths of 1,000 randomly selected reinforcing fibers (A) are measured, and the weight-average fiber length (Lw) is calculated using the above formula. The filter paper used here may be quantitative filter paper (model number: No. 5C) manufactured by Advantec Co., Ltd.

[0046] When the molding material for the artificial feather of the present invention contains two types of reinforcing fibers, it may be a dry blend of, for example, long fiber pellets in which the fibers are aligned in the longitudinal direction of the fibers of the molding material and short fiber pellets in which the fibers within the molding material are randomly oriented. The long fiber pellets are preferably long fiber pellets produced using known techniques, in which the reinforcing fibers (A) are coated with a polymer alloy (B). The short fiber pellets may also be produced using known techniques. For example, short fiber pellets produced by melt-kneading the reinforcing fibers (A) and the polymer alloy (B) in a twin-screw extruder and then pelletizing them are exemplified. Unlike melt-kneading, dry blending refers to stirring and mixing multiple materials at a temperature at which the resin components do not melt to produce a substantially uniform mixture. This dry blending is preferably used when using pellet-shaped molding materials, such as injection molding or extrusion molding.

[0047] The molding material for molding the feather shaft portion 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 Furthermore, by using a material that has a water absorption rate of 1.5% or less when left for 24 hours in an environment of 80°C x 95% RH and a flexural modulus of elasticity at atmospheric equilibrium water absorption of 5.3 GPa or more, stable flight characteristics, particularly deceleration performance, can be obtained, and high durability that will not break even after repeated impacts can be achieved.

[0048] The feathers used in natural feather shuttlecocks have a low specific gravity and are extremely lightweight. Furthermore, the feather rachis is highly rigid and returns to its original shape regardless of the number of cumulative strikes. For this reason, natural feather shuttlecocks have unique flight performance, with a high initial speed and braking ability, particularly high deceleration performance. On the other hand, if the rigidity of the feather rachis is increased in an artificial shuttlecock using artificial feathers, the weight increases and the weight balance deteriorates. For this reason, the flight performance of natural feather shuttlecocks cannot be obtained. Furthermore, if the weight of the feather rachis is reduced, the rigidity decreases, and the return after strike is slower. This results in a decrease in flight performance, particularly deceleration performance.

[0049] If the molding material used to mold the feather shaft portion of the artificial feather of the present invention has a specific gravity of more than 1.21, the weight balance of the artificial feather shuttlecock will be poor and flight stability, particularly deceleration performance, may decrease, so it is more preferable that the specific gravity be 1.20 or less. ２ If it is less than 77 kJ / m, repeated impacts may cause the blade shaft to break and reduce durability. ２ or more is more preferable. Furthermore, if the water absorption rate of the artificial feather exceeds 1.5% and the flexural modulus at atmospheric equilibrium water absorption is less than 5.3 GPa, the return of the feather shaft after bending during impact will be slow, which may result in poor flight performance. A water absorption rate of 1.4% or less is more preferable. Furthermore, the flexural modulus at atmospheric equilibrium water absorption is more preferably 5.5 GPa or more, and even more preferably 5.9 GPa.

[0050] Methods that can be used to mold the artificial feathers include insert molding, in which the impeller is fitted into the cavity while the mold is open and then the mold is closed to injection mold the impeller, and two-shot molding, in which the impeller and impeller are alternately molded in one cycle using resins of different materials or different colours to form the artificial feather. Although the impeller and impeller can be integrated using insert molding, it is preferable to use two-shot molding from the standpoint of production efficiency.

[0051] By using a molding material having the above properties, it is possible to improve the flight performance, particularly the deceleration performance, of the artificial shuttlecock and also to suppress the occurrence of breakage of the blade shaft portion.

[0052] By using the molding material described above, the artificial feather of the present invention is able to exhibit high durability and excellent flight performance, particularly deceleration performance, and is therefore useful as a substitute for natural shuttlecock feathers.

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the descriptions of these examples. First, the methods for evaluating various properties used in the examples will be described.

[0054] (1) Weight average fiber length Test pieces cut out from the molded product were placed in a solvent in which the resin composition used in each Example and Comparative Example was dissolved, and then heated appropriately to obtain a solution in which the reinforcing fiber (A) was uniformly dispersed. Then, using quantitative filter paper (No. 5C) manufactured by Advantec Co., Ltd., the solution was filtered, and the reinforcing fiber (A) dispersed on the filter paper was observed under an optical microscope (50 to 200 times). The fiber lengths of 1,000 randomly selected reinforcing fibers (A) were measured, and the weight average fiber length (LwA1) was calculated using the following formula. Average fiber length = Σ(Mi ２ × Ni) / Σ(Mi × Ni) Mi: fiber length [mm] Ni: number of fibers with fiber length Mi

[0055] (2) Measurement of flexural strength and flexural modulus of molded products, and flexural modulus upon water absorption. For the ISO dumbbell test specimens obtained in each example and comparative example, flexural strength and flexural modulus were measured in accordance with ISO 178:2010, Amd. 1:2013 using a three-point bending test jig (indenter radius 5 mm) with a support distance of 64 mm and a test speed of 2 mm / min. The tester used was an "Instron (registered trademark)" universal testing machine, Model 5566 (manufactured by Instron Corporation). Measurements were performed three times, and the average values ​​were calculated as the flexural strength and flexural modulus for each example and comparative example. The flexural modulus was calculated from the stress gradient in the specified strain range (0.05 to 0.25%). The flexural modulus was also measured in the same manner as above for the water-absorbed ISO dumbbell test specimens described below.

[0056] (3) Measurement of Charpy impact strength of molded products A parallel portion was cut out from the ISO dumbbell test specimen obtained in each example and comparative example, and a notched Charpy impact test was carried out in accordance with ISO179 using a C1-4-01 model testing machine manufactured by Tokyo Test Instruments Co., Ltd., to measure the impact strength [kJ / cm ２ ] was calculated.

[0057] (4) Morphology Observation The central portion of the cross section of a JIS-5A dumbbell-shaped test specimen or a bending test specimen obtained by injection molding was cut into 1-2 mm squares and stained with ruthenium tetroxide to stain the second resin (Bb) having a reactive functional group. The test specimen was cut using an ultramicrotome at -196°C to obtain ultrathin sections with a thickness of 0.1 μm or less (approximately 80 nm). The sections were observed using a transmission electron microscope. The number average particle size (Xn) was calculated by randomly extracting 400 or more particles from the obtained image and analyzing the particle size distribution using image analysis software "Scion Image" manufactured by Scion Corporation, using the following formula: Number average particle size (Xn) = Σ(Xi × ni) / Σni Xi: particle size ni: number of particles corresponding to particle size (Xi) (i = 1, 2, 3, ..., n)

[0058] The number average particle size of the particles made of the second resin (Bb) is calculated from an image magnified 10,000 times, and the number average particle size of the fine particles contained in the second resin (Bb) is calculated from an image magnified 35,000 times. The presence or absence of fine particles having a number average particle size of 1 to 100 nm contained in the second resin (Bb) was confirmed.

[0059] (5) Water Absorption Measurement The ISO dumbbell test pieces obtained in each Example and Comparative Example were left to stand in a thermostatic chamber at 23°C and 50% humidity for 24 hours, after which their weights were measured, and then they were left in an environment of 80°C and 95% RH for 24 hours. After that, the water from the obtained water-absorbed ISO dumbbell test pieces was wiped off and then weighed, and the water absorption rates of the ISO dumbbell test pieces before and after water absorption were calculated.

[0060] (6) Evaluation of Deceleration Performance of Artificial Shuttlecock The flight speed of the artificial shuttlecock obtained in each example was measured by hitting it with a string strung on a carbon racket rotating at a speed of 230 km / h. The artificial shuttlecock flying in a straight line after being hit was photographed using a high-speed camera at a frame rate of 5000 fps, and the average speed of the artificial shuttlecock (average speed over 10 m from the hit position) was calculated using the following formula. The average speed was measured for a sample number of N = 3, and the average value calculated was evaluated according to the following criteria: Average speed over 10 m (km / h) = 0.01 km / Time to reach 10 m (h) Final speed less than 90 km / h: ◯ (pass) Final speed 90 km / h or more: × (fail)

[0061] (7) Durability Evaluation of Artificial Shuttlecocks The durability of the artificial shuttlecocks obtained in each Example was measured by curing them for 12 hours in an environment with a temperature of 5°C and a humidity of 30%, and then hitting them with a string strung on a carbon racket rotating at a speed of 230 km / h in the same environment. The number of hits until the shaft broke was evaluated according to the following criteria, with △ and ◯ being considered pass. No shaft breakage or damage after 50 or more hits: ◯ (Excellent) No shaft breakage or damage after 45 or more hits: △ (Good) Shaft breakage or damage after less than 45 hits: × (Fail)

[0062] (Reference Example 1) [Preparation of Carbon Fiber (A1)] A copolymer containing polyacrylonitrile as the main component was spun, calcined, and surface-oxidized to prepare a carbon fiber (A1) having a total of 24,000 single fibers, a single fiber diameter of 7 μm, a mass per unit length of 1.6 g / m, and a specific gravity of 1.8 g / cm. ３ and a surface oxygen concentration ratio [O / C] of 0.2, resulting in continuous carbon fibers. The strand tensile strength of this continuous carbon fiber was 4,880 MPa, and the strand tensile modulus was 225 GPa. Next, a sizing agent mother solution was prepared by dissolving glycerol polyglycidyl ether as a polyfunctional compound in water to a concentration of 2 wt %, and the sizing agent was applied to the carbon fibers by a dipping method, followed by drying at 230°C. The amount of sizing agent attached to the carbon fibers thus obtained was 1.0 wt %.

[0063] [Glass Fiber (A2)] Glass fiber "T-249" (manufactured by Nippon Electric Glass Co., Ltd.) was used.

[0064] [Thermoplastic Resin (Ba)] (Ba-1) A polyamide resin (manufactured by Toray Industries, Inc., nylon 610 resin "Amilan" (registered trademark) CM2001) was used.

[0065] [Second Resin (Bb) Having Reactive Functional Group] (Bb-1) A maleic anhydride-modified ethylene-1-butene copolymer "TAFMER" (registered trademark) MH7020 (manufactured by Mitsui Chemicals, Inc.) was used.

[0066] Example 1 A long-fiber reinforced resin pellet manufacturing apparatus equipped with a coating die for a wire coating method installed at the tip of a TEX-30α twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) (screw diameter 30 mm, L / D = 32) was used. The extruder cylinder temperature was set to 260°C, and a resin composition consisting of at least the thermoplastic resin (Ba-1) and the second resin (Bb) described above was fed from the main hopper and melt-kneaded. The molten thermoplastic resin was continuously placed so as to coat the periphery of the carbon fiber (A1). The resulting strand was cooled and then cut with a cutter to pellets with a length of 7 mm to obtain long-fiber pellets (A1-1). The take-up speed was adjusted so that the carbon fiber (A1-1) was 30 parts by weight per 100 parts by weight of the total of the reinforcing fiber (A) and the resin composition. The length of the carbon fiber (A1) in the obtained long-fiber pellets (A1-1) was substantially the same as the pellet length.

[0067] On the other hand, a resin composition consisting of glass fiber (A2) and at least the thermoplastic resin (Ba-1) and second resin (Bb) described above was extruded into a co-rotating, fully intermeshing twin-screw extruder (manufactured by The Japan Steel Works, Ltd., TEX-65αII) with a screw diameter of 65 mm and two double-start screws, L / D = 35, and a strand of molten resin was extruded. The screw configuration at this time included three kneading zones starting at positions L / D = 7, 16, and 25, with the lengths Lk / D of each kneading zone being Lk / D = 3.0, 3.0, and 3.0, respectively. Furthermore, a reverse screw zone was provided downstream of each kneading zone, and the lengths Lr / D of each reverse screw zone were Lr / D = 0.5, 0.5, and 0.5, respectively. A vent vacuum zone was provided at a position L / D = 30, and volatile components were removed at a gauge pressure of -0.1 MPa. The molten resin discharged from the die head through 4 mmφ x 23 holes was pulled into strands, cooled through a cooling bath, and cut into pieces while being taken up by a pelletizer, to obtain short glass fiber pellets (A2-1). The pellets were vacuum dried at 80 ° C for 12 hours or more, then dry-blended with the long fiber pellets in the ratios shown in Table 1, and injection-molded using an injection molding machine (manufactured by The Japan Steel Works, Ltd., J110AD) under the following conditions: injection time: 2 seconds, back pressure: 5 MPa, dwell pressure: 40 MPa, dwell time: 10 seconds, cylinder temperature: 260 ° C, mold temperature: 60 ° C. ISO dumbbell test pieces were produced as molded articles. Here, the cylinder temperature refers to the temperature of the part of the injection molding machine where the molding material is heated and melted, and the mold temperature refers to the temperature of the mold into which the resin is injected to form the desired shape. The obtained test pieces (molded articles) were left to stand for 24 hours in a constant temperature and humidity chamber adjusted to a temperature of 23°C and a relative humidity of 50%, and then subjected to evaluation of the properties. The evaluation results obtained by the above-mentioned methods are summarized in Table 1.

[0068] Furthermore, artificial feather 1 (feather shank 1a and feather aerofoil 1b) shown in FIG. 1 and artificial shuttlecock 11 shown in FIG. 2 were produced using the proportions shown in Table 1 by the following method, and the shuttlecock deceleration performance evaluation and durability evaluation described above were carried out.

[0069] [Method of Producing Artificial Feathers] Artificial feather 1 was molded by two-shot molding using two injection molding machines (injection molding machine I and injection molding machine II). First, using injection molding machine II, resin pellets were injection molded into a mold containing vane shaft portion 1a molded by injection molding machine I, under conditions of an injection time of 0.2 seconds, a back pressure of 3 MPa, a dwell pressure of 65 MPa, a dwell time of 0.2 seconds, a cylinder temperature of 215°C, and a mold temperature of 60°C, thereby molding vane aerofoil portion 1b. Next, long fiber pellets (A1-1) and short glass fiber pellets (A2-1) were blended, and the blend was injection molded using injection molding machine I under conditions of an injection time of 0.2 seconds, a back pressure of 7 MPa, a dwell pressure of 130 MPa, a dwell time of 1.8 seconds, a cylinder temperature of 285°C, and a mold temperature of 60°C, thereby molding vane shaft portion 1a and producing artificial feather 1.

[0070] [Method of Producing an Artificial Feather Shuttlecock] Feather shaft portions 1a of a plurality of artificial feathers 1 produced by the method described above were embedded in a circular shape along the circumference of the flat surface of base portion 2, which was constructed by covering a cork base with a thin leather. Base portion 2 was hemispherical in shape, with a diameter of 25 mm to 28 mm, and had a flat surface. Furthermore, a plurality of artificial feathers 1 were arranged so that the intervals between them increased with increasing distance from base portion 2, and each artificial feather 1 was arranged so that it overlapped with an adjacent artificial feather 1. In this way, skirt portion 4 was formed by a plurality of artificial feathers 1, and artificial feathers 1 were secured together with string-like member 3, thereby producing artificial feather shuttlecock 11.

[0071] (Examples 2 to 4, Comparative Examples 1 and 3) ISO test specimens and artificial shuttlecocks were prepared and evaluated in the same manner as in Example 1, except that the composition ratios were changed as shown in Table 1. The evaluation results are summarized in Table 1.

[0072] Comparative Example 2 The carbon fiber (A1) bundle and thermoplastic resin (Ba-1) described above were fed from the main hopper of a Japan Steel Works, Ltd. TEX-30α type twin-screw extruder (screw diameter 30 mm, L / D = 32). The screw rotation speed was set to 200 rpm, and the mixture was melt-kneaded in the cylinder. The molten resin passed through the die head and discharged from 4 mmφ x 23 holes was drawn into a strand shape, cooled by passing through a cooling bath, and cut into pieces while being taken up by a pelletizer, thereby obtaining short carbon fiber pellets (A2-1). The pellets were vacuum-dried at 80°C for 12 hours or more and then dry-blended with the short glass fiber pellets (A2-1) in the ratios shown in Table 1. ISO test specimens and artificial shuttlecocks were prepared and evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 1.

[0073] In Example 1, the molding material exhibited high impact strength and an excellent flexural modulus when water was absorbed, and as a result, the durability of the artificial shuttlecock passed a test of more than 50 hits, and the average speed when reaching a point 10 m from the impact point was 88 km / h or less, resulting in excellent deceleration performance. Furthermore, Examples 2 to 4, in which the contents of carbon fiber (A1) and glass fiber (A2) were changed, also exhibited high impact strength and an excellent flexural modulus when water was absorbed, and as a result, the flight performance of the artificial shuttlecock was also excellent.

[0074] On the other hand, in Comparative Example 1, because the carbon fiber (A1) was not contained, the fiber reinforcement effect was weak and the flexural modulus when absorbing water as a molding material was insufficient, resulting in a low deceleration performance of the artificial shuttlecock, i.e., a high average speed at 10 m. Furthermore, in Comparative Example 2, because short carbon fiber pellets (A1-2) were used, the weight average fiber length (LwA1) in the molded product was short and the unnotched Charpy impact strength was low, resulting in a decrease in the durability of the artificial shuttlecock. Furthermore, in Comparative Example 3, because the resin (Bb-1) having a reactive functional group was not contained, the toughness as a molding material was reduced, resulting in poor impact strength of the molded product and a decrease in the durability of the artificial shuttlecock.

[0075]

[0076] The artificial shuttlecock feathers of the present invention have excellent durability and flight performance, and in particular deceleration performance, and are therefore suitable for use as parts to replace the feather shanks of natural shuttlecocks.

[0077] REFERENCE SIGNS LIST 1 artificial feather 1a feather shaft portion 1b feather wing portion 2 base portion 3 string-like member 4 skirt portion 11 artificial shuttlecock

Claims

1. An artificial shuttlecock feather comprising a feather shank portion made of reinforcing fiber (A) containing at least carbon fiber (A1) and a polymer alloy (B), and a feather aerofoil portion supported by the feather shank portion, the artificial shuttlecock feather comprising: 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) per 100 parts by weight total of the reinforcing fiber (A) and the polymer alloy (B); and the weight average fiber length (LwA1) of the carbon fiber (A1) is 0.5 to 7.0 mm.

2. The artificial shuttlecock feather as recited in claim 1, wherein the polymer alloy (B) comprises a continuous phase (P1) and a disperse phase (P2), the disperse phase (P2) being dispersed in the continuous phase (P1) in the form of particles with a dispersion diameter of 10 to 1,000 nm.

3. The artificial shuttlecock feather according to claim 1 or 2, wherein the dispersed phase (P2) contains fine particles having a particle diameter of 1 to 100 nm.

4. The blade shaft has a specific gravity of 1.21 or less and a non-notched Charpy impact strength of 75 kJ / m ２ 3. The artificial shuttlecock feather according to claim 1 or 2, comprising a molding material having a water absorption rate of 1.5% or less when left for 24 hours in an environment of 80°C x 95% RH and a flexural modulus of elasticity at atmospheric equilibrium water absorption of 5.3 GPa or more.

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