EP3997261A1 - Monofilament string for a racket - Google Patents
Monofilament string for a racketInfo
- Publication number
- EP3997261A1 EP3997261A1 EP20736738.4A EP20736738A EP3997261A1 EP 3997261 A1 EP3997261 A1 EP 3997261A1 EP 20736738 A EP20736738 A EP 20736738A EP 3997261 A1 EP3997261 A1 EP 3997261A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- polyamide
- string
- sheath
- graphene
- core
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 79
- 229910021389 graphene Inorganic materials 0.000 claims abstract description 68
- 239000000463 material Substances 0.000 claims abstract description 55
- 229920002647 polyamide Polymers 0.000 claims abstract description 47
- 239000004952 Polyamide Substances 0.000 claims abstract description 44
- 239000002105 nanoparticle Substances 0.000 claims abstract description 31
- 229920000997 Graphane Polymers 0.000 claims abstract description 30
- 229920002292 Nylon 6 Polymers 0.000 claims description 44
- 229920001577 copolymer Polymers 0.000 claims description 24
- 238000001125 extrusion Methods 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 13
- 230000008569 process Effects 0.000 claims description 13
- 239000000654 additive Substances 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000003795 chemical substances by application Substances 0.000 claims description 5
- 230000002209 hydrophobic effect Effects 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 239000012748 slip agent Substances 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 4
- 229920000571 Nylon 11 Polymers 0.000 claims description 3
- 229920000299 Nylon 12 Polymers 0.000 claims description 3
- 229920002302 Nylon 6,6 Polymers 0.000 claims description 3
- 239000011159 matrix material Substances 0.000 description 16
- 229920000642 polymer Polymers 0.000 description 12
- 238000012423 maintenance Methods 0.000 description 8
- 239000004033 plastic Substances 0.000 description 7
- 229920003023 plastic Polymers 0.000 description 7
- 239000002245 particle Substances 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 5
- -1 polyethylene Polymers 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 3
- 239000011852 carbon nanoparticle Substances 0.000 description 3
- 239000002041 carbon nanotube Substances 0.000 description 3
- 229910021393 carbon nanotube Inorganic materials 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 239000011737 fluorine Substances 0.000 description 3
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 3
- 229910052982 molybdenum disulfide Inorganic materials 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229920000271 Kevlar® Polymers 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 208000027418 Wounds and injury Diseases 0.000 description 2
- 239000004205 dimethyl polysiloxane Substances 0.000 description 2
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 2
- 239000002360 explosive Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229920001519 homopolymer Polymers 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000004761 kevlar Substances 0.000 description 2
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- FUSNPOOETKRESL-ZPHPHTNESA-N (z)-n-octadecyldocos-13-enamide Chemical compound CCCCCCCCCCCCCCCCCCNC(=O)CCCCCCCCCCC\C=C/CCCCCCCC FUSNPOOETKRESL-ZPHPHTNESA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 235000009854 Cucurbita moschata Nutrition 0.000 description 1
- 240000001980 Cucurbita pepo Species 0.000 description 1
- 235000009852 Cucurbita pepo Nutrition 0.000 description 1
- UAUDZVJPLUQNMU-UHFFFAOYSA-N Erucasaeureamid Natural products CCCCCCCCC=CCCCCCCCCCCCC(N)=O UAUDZVJPLUQNMU-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229920000426 Microplastic Polymers 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 208000002240 Tennis Elbow Diseases 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229920001400 block copolymer Polymers 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- UAUDZVJPLUQNMU-KTKRTIGZSA-N erucamide Chemical compound CCCCCCCC\C=C/CCCCCCCCCCCC(N)=O UAUDZVJPLUQNMU-KTKRTIGZSA-N 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- RKISUIUJZGSLEV-UHFFFAOYSA-N n-[2-(octadecanoylamino)ethyl]octadecanamide Chemical compound CCCCCCCCCCCCCCCCCC(=O)NCCNC(=O)CCCCCCCCCCCCCCCCC RKISUIUJZGSLEV-UHFFFAOYSA-N 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920006149 polyester-amide block copolymer Polymers 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 230000001846 repelling effect Effects 0.000 description 1
- 229920006126 semicrystalline polymer Polymers 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 235000020354 squash Nutrition 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
- D01F6/60—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides
-
- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B51/00—Stringing tennis, badminton or like rackets; Strings therefor; Maintenance of racket strings
- A63B51/02—Strings; String substitutes; Products applied on strings, e.g. for protection against humidity or wear
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F1/00—General methods for the manufacture of artificial filaments or the like
- D01F1/02—Addition of substances to the spinning solution or to the melt
- D01F1/10—Other agents for modifying properties
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
- D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
- D01F8/12—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyamide as constituent
-
- D—TEXTILES; PAPER
- D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
- D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
- D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
- D02G3/44—Yarns or threads characterised by the purpose for which they are designed
- D02G3/444—Yarns or threads for use in sports applications
-
- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B2209/00—Characteristics of used materials
-
- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B2209/00—Characteristics of used materials
- A63B2209/02—Characteristics of used materials with reinforcing fibres, e.g. carbon, polyamide fibres
-
- D—TEXTILES; PAPER
- D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
- D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
- D10B2101/00—Inorganic fibres
- D10B2101/10—Inorganic fibres based on non-oxides other than metals
- D10B2101/12—Carbon; Pitch
- D10B2101/122—Nanocarbons
-
- D—TEXTILES; PAPER
- D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
- D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
- D10B2331/00—Fibres made from polymers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polycondensation products
- D10B2331/02—Fibres made from polymers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polycondensation products polyamides
Definitions
- the present invention relates to a monofilament string and a set of such strings for a racket such as a tennis racket, a squash racket, a badminton racket, or the like.
- a racket In the field of racket sports, a racket is made of a handle and a hoop, a set of strings extending in two orthogonal directions across the hoop and being intended to undergo the impact of a ball, a shuttlecock or the like.
- Power properties refer to the ability of the strings to increase the speed of the ball getting out of the strings when the player hits the ball.
- Control properties refer to the ability of the strings to influence the behavior of the ball, thus resulting in the possibility for the player to hit the ball towards a predetermined position with accuracy, to slow down the ball, and to influence the spin of the ball.
- Comfort properties refer to the ability of the strings to reduce the vibrations of the racket resulting from the strings undergoing the impact of the ball when the player hits the ball.
- durability properties refer to strings having a reduced degradation of their structure over time and use, which results in particular in a reduced tension loss, thus allowing them to keep their power, control, and/or comfort properties.
- strings made of natural guts have a low stiffness, which allows the player to accelerate the ball with no need of a high physical strength.
- they provide a poor control of the ball.
- multifilament strings usually made of polyamide.
- Monofilament and multifilament strings are usually made of polyethylene, polyester, or polyamide. Strings made of polyethylene and polyester have a high stiffness, which allow the player to be precise and to have a good control of the ball. However, the player needs to have a high physical strength in order to accelerate the ball. Strings made of polyamide show these characteristics while providing a great ability to dissipate the vibrations of the racket as well, but tend to degrade and to lose tension fast.
- monofilament strings that show a good balance between power and control properties, while having also good comfort and durability properties.
- monofilament strings that show high power properties so that the player can easily increase the speed of the ball with no need of a high physical strength, while allowing the player to have a good control of the ball, and that maintain a substantially constant tension over time for a reasonable amount of time (preferably the time of a match, which is several hours, notably 2 to 4 hours, for an experienced player).
- the document FR 2 934 958 aims to enhance the durability of a racket string, and discloses a monofilament string that comprises a central core, a peripheral protective layer, and an intermediate reinforcing layer made of a composite material, positioned between the central core and the peripheral protective layer.
- the intermediate reinforcing layer increases the durability of the strings by increasing their rigidity at the expense of their elasticity, but this causes the strings to have reduced power properties as their ability to bend at the impact of a ball is reduced.
- the document WO2018234376 discloses monofilament strings that improve the balance between power and control properties. However, the durability of the strings over time and use needs to be further improved.
- Carbon nanotubes have been reported in documents US 2008/0206559 and US 2012/0237767 as an additive in a wear-resistant coating wrapped around a multi-filament string.
- carbon nanotubes substantially rigidify the material in which they are included and thus render it difficult to process.
- An object of the invention is to provide a monofilament string that overcomes the above-mentioned drawbacks.
- the invention especially aims to provide a monofilament string that show a good balance between power and control properties, while having also good comfort and durability properties, and enhanced durability over time and use compared to the existing strings, while allowing its manufacturing by a co-extrusion process.
- one object of the invention is a monofilament string for a racket, comprising a core consisting of a single filament and a sheath extending around the core and in contact with the core, wherein:
- the core is made of a first material comprising at least a polyamide
- the sheath is made of a second material comprising at least a polyamide
- the second material is a polyamide matrix comprising graphene or graphane nanoparticles with a concentration ranging from 0.1% to 5% in weight, preferably from 0.1% to 2% in weight, and more preferably from 0.1 % to 1 % in weight of the weight of the sheath.
- polyamide matrix is meant in the present text a matrix comprising at least one polyamide homopolymer and/or copolymer.
- the matrix may include PA6, PA6.6, PA11 , PA12, PA4.6 and/or copolymers thereof.
- the matrix may include other polymers, the total weight percent of polyamide being greater than the total weight percent of the other polymer(s).
- the matrix may also include fillers or additives.
- the characteristics of the string remains substantially the same in terms of comfort, control and power.
- durability the string over time and use i.e. their ability not to deteriorate, improves significantly.
- the graphene or graphane content is chosen sufficiently low to allow manufacturing the monofilament by a co-extrusion process.
- the monofilament has to be stretched to present the required mechanical properties.
- An excessive graphene or graphane content provides an excessive rigidity of the material during the co-extrusion process, which impedes a suitable stretching, resulting in poor mechanical properties of the monofilament.
- the monofilament can be stretched during the co-extrusion process to a sufficient extent and thus achieve the required mechanical properties.
- Graphene is an allotrope of carbon in the form of a two-dimensional, atomic-scale, hexagonal lattice in which one atom forms each vertex.
- Graphane is a form of hydrogenated graphene. More precisely, graphane is a two- dimensional polymer of carbon and hydrogen with the formula unit (CH) n where n is a large integer.
- Such graphene or graphane nanoparticles allow for stabilizing the structure of the string, and the nanometric size of the carbon particles does not severely stiffen the string, contrary to certain other additives based on fluorine, molybdenum disulfide or Kevlar fiber in particular.
- the graphene nanoparticles also improve the temperature resistance as well as the slipping of one string onto another, which is also directed towards the improvement of the stability over time by avoiding premature degradation of the string.
- rigidity refers to the tensile modulus (also called“Young’s modulus” or modulus of elasticity”) of a material.
- a material with a high rigidity presents a high tensile modulus and thus a low elasticity.
- geometric stiffness or simply“stiffness”, used herein is similar to the term “rigidity” but relates to a structure.
- the stiffness of the structure depends on the rigidity of the material it is made of and on its dimensional characteristics.
- the second material comprises at least one of: polyamide 6, polyamide 6.6, polyamide 11 , polyamide 12, polyamide 66, and their mixtures;
- the first material comprises polyamide 6 and a first copolymer of polyamide 6 and polyamide 6.6, and the second material comprises a second copolymer of polyamide 6 and polyamide 6.6;
- the first material has a greater tensile modulus than the second material
- the second material further comprises at least one additive selected from the group consisting of: slip agents and hydrophobic agents.
- Another object of the invention is a racket comprising a set of monofilaments strings described previously.
- Another object of the invention is a process for manufacturing a monofilament as described above.
- the core and the sheath are formed by a co-extrusion process.
- Said process further includes stretching the monofilament.
- FIG. 1 is a cross-sectional view of a second embodiment of the monofilament string of the invention, wherein the monofilament string comprises a core and sheath, and the sheath includes graphene or graphane nanoparticles;
- FIG. 2 is a schematic view of a racket comprising a set of monofilament strings according to the invention
- FIG. 3 is a graph representing the influence of graphene nanoparticles in the tensile strength for different monofilament strings
- FIG. 4 is a graph representing the influence of graphene nanoparticles in the module of the tensile stress for different monofilament strings;
- FIG. 5 is a graph representing the influence of graphene nanoparticles in the mechanical resistance in tension for different monofilament strings
- FIG. 6 is a graph representing the influence of graphene nanoparticles in the elongation for different monofilament strings
- FIG. 7 is a graph representing the influence of graphene nanoparticles in the plastic deformation for different monofilament strings.
- the invention proposes a monofilament string for a racket.
- the monofilament string comprises a core and a sheath coaxial with the core and which is made of a polyamide matrix including graphene or graphane nanoparticles.
- the polyamide matrix comprises at least one polyamide homopolymer and/or copolymer, which are preferably selected among the following: polyamide 6, polyamide 6.6, polyamide 1 1 , polyamide 12, polyamide 66, and their mixtures.
- the matrix may include other polymer(s) that polyamide polymers. However, the total weight percent of polyamide is always greater than the total weight percent of the other polymer(s).
- the polyamide matrix may also include fillers or additives.
- the polyamide matrix provides the monofilament string with high stiffness, which allows the player to be precise and to have a good control of the ball, and a great ability to dissipate the vibrations of the racket which improves the comfort.
- the presence of graphene or graphane nanoparticles in the polyamide matrix maintains the good properties provided by the polyamide matrix, while strongly increasing the durability of the string over time and use.
- the set of strings of a racket maintain their good characteristics in terms of comfort, control and power for an improved period of time, and the breakage of the strings is strongly reduced, if not prevented, even when the strings are highly stressed. In other terms, the ability of the strings not to deteriorate improves significantly.
- a quantity of 20% or less in weight of graphene or graphane nanoparticles relative to the weight of the portion including said nanoparticles is optimal to confer the string enhanced durability without increasing the stiffness too much.
- the weight percentage of the graphene or graphane nanoparticles ranges from 0.1 % to 5%, more preferably from 0.1 % to 2%, and even more preferably from 0.1% to 1%.
- Graphene and graphane are perfectly adapted to be incorporated within the polyamide matrix and all of them provide the string with the enhanced durability property.
- Graphene and graphane particles are considered as bi-dimensional (2D) particles since they have a sheet-like structure extending in a plane.
- carbon nanotubes that are other types of carbon nanoparticles, are three-dimensional (3D) particles since they can be considered as carbon sheets wound on themselves to form cylinders.
- the enhanced durability comes from the specific mechanical and thermal properties of the carbon nanoparticles.
- Graphene and graphane nanoparticles are also very light.
- the density of graphene is about 2.25 g/cm 3 , which is very low.
- graphene and graphene nanoparticles used in a suitable concentration as mentioned above, show high rigidity and lightness, thereby stabilizing the structure of the string without severely stiffening the string, contrary to certain other additives based on fluorine, molybdenum disulfide or Kevlar fiber in particular.
- graphene and graphane nanoparticles provide the string with good slipping properties, which reduces the friction between the strings when slipping.
- Graphene and graphane nanoparticles show high thermal conductivity and thermal stability.
- the value of the thermal conductivity of graphene is about 5000 W.nr 1 .K 1 , which is 10 times higher than copper, 20 times higher than aluminum, and 2 times higher than graphite.
- graphene and graphane nanoparticles provide the string with an increased ability to regulate and distribute heat in the set of strings of the racket.
- FIG. 1 An embodiment of the monofilament string of the invention is illustrated in figure 1.
- the monofilament string 1 comprises a core 2 consisting of a single filament, and a sheath 3 extending around the core and in contact with the core.
- the core 2 has a round cross section and the sheath 3 has an annular cross section, the sheath being coaxial with the core.
- the core 2 is made of a first material comprising a first copolymer of polyamide 6 and polyamide 6.6 (first copolymer PA 6/6.6), and the sheath is made of a second material comprising a second copolymer of polyamide 6 and polyamide 6.6 (second copolymer PA 6/6.6, which may be the same as the first copolymer).
- Polyamide 6 and polyamide 6.6 are thermoplastic semi-crystalline polymers that exhibit good mechanical properties. They are both quite rigid polymers although polyamide 6 has a higher tensile modulus than polyamide 6.6.
- the tensile modulus of the polyamide 6 generally ranges between 700
- the polyamide matrix including the graphene or graphane nanoparticles is in the sheath.
- the polyamide matrix including the graphene or graphane nanoparticles is in both the core and the sheath.
- the graphene or graphane nanoparticles are only in the sheath, and represent from 0.1 % to 5% in weight, preferably from 0.1 % to 2% in weight, and more preferably from 0.1 % to 1 % in weight of the weight of the sheath.
- the mechanical properties of the copolymer PA 6/6.6 generally lie somewhere between those of the polyamide 6 and the polyamide 6.6.
- a block-copolymer PA 6/6.6 is preferred because the properties of the latter can be very close to the better properties of the polyamide 6 and the polyamide 6.6 without suffering from a corresponding loss in other desired properties, depending on the structure of the copolymer PA 6/6.6, the respective proportions of polyamide 6 and polyamide 6.6 in the copolymer PA 6/6.6, and the process of manufacturing of the copolymer PA 6/6.6.
- the copolymer PA 6/6.6 has a tensile strength comprised between that of the polyamide 6 and the polyamide 6.6, or substantially equal to that of the polyamide 6.6.
- the first material is preferably selected so as to have a greater tensile modulus than that of the second material.
- the first material comprises, in addition to the first copolymer PA 6/6.6, polyamide 6.
- Polyamide 6 provides the first material with a high rigidity, as well as a strong ability to dissipate the mechanical efforts (energy) when deformed elastically.
- the core 2 thus provides the monofilament string 1 with a high geometric stiffness and the ability to strongly absorb/dissipate the mechanical efforts applied to it that occur when the string undergoes the impact of a ball or the like, which results in a better control of the ball as well as a reduction of the vibrations that propagate through the sieve 8 and the handle 9 of the racket 5 represented in figure 2.
- the racket 5 allows the player to slow down the ball after receiving and hitting the ball for a better control of the ball. Another result is that the player receives fewer vibrations and shocks when hitting the ball for a better comfort thus preventing injuries such as tennis elbow for example in the case of a tennis racket.
- the sheath does not contain polyamide 6.
- the second material can possibly comprise polyamide 6, but in a significantly lower amount compared to the first material. In this situation, the percentage by weight of polyamide 6 in the second material (relative to the second material) is significantly lower than the percentage by weight of polyamide 6 in the first material (relative to the first material).
- the amount of polyamide 6 in the copolymers PA 6/6.6 of the first and second materials is also adjusted so that the tensile modulus of the first material is greater than the tensile modulus of the second material.
- the percentage by weight of polyamide 6 in the copolymer PA 6/6.6 of the second material is lower than the percentage by weight of polyamide 6 in the copolymer PA 6/6.6 of the first material.
- the second material sheath
- the second material has a lower tensile modulus than the first material (core).
- the second material is more elastic, absorbs less energy when deformed elastically and releases more energy than the first material.
- the sheath 3 thus provides the monofilament string 1 with the ability to strongly release the mechanical efforts applied to said string when the string undergoes the impact of a ball or the like.
- the string 1 is preferably obtained by co-extrusion of the core 2 and the sheath 3. Coextruding the core 2 and the sheath 3 forms an interface 4 at the contact zone between the core and the sheath where said core and sheath are intimately linked.
- the core 2 and the sheath 3 of the string 1 have similarities in terms of chemical structure. Both the core and the sheath indeed are made of a polyamide-based material, namely a copolymer PA 6/6.6.
- the strong mechanical and chemical cohesion of the core 2 and the sheath 3 at the interface 4 allows said core and sheath to act in synergy when the string is requested mechanically, thus further improving the overall mechanical properties of the string, in particular its durability as well as its ability to influence the spin of the ball.
- the weight proportion of the sheath 3 is small compared to the weight proportion of the core 2.
- the sheath preferably represents from 5% to 20% by weight, more preferably from 8% to 16% by weight, of the total weight of the string 1.
- the core preferably represents from 80% to 95% by weight, more preferably from 84% to 92% by weight, of the total weight of the string.
- the thickness of the sheath 3 represents from 2% to 7%, preferably from 3% to 6%, of the total thickness of the string 1
- the thickness of the core 2 represents from 93% to 98%, preferably from 94% to 97%, of the total thickness of the string 1.
- the thickness of the sheath ranges preferably from 20 and 50 micrometers while the thickness (which corresponds to the diameter) of the core ranges from 1200 and 1500 micrometers.
- Such high weight proportion of the core relative to the sheath allows, along with the composition of the first and second materials of the core and the sheath, having a string with high control properties.
- the sheath is however sufficient to provide the string with high power properties, in particular by imparting to the string explosive properties.
- explosive is meant in the present text that the racket returns the ball with a great speed. The combination of the core and sheath thus provides a good balance between control properties and power properties.
- compositions and proportions of the core and the sheath may be adjusted to provide an optimal trade-off between control and power properties.
- the sheath advantageously comprises one or more additive(s) that facilitate the slipping of the strings relative to each other thus providing the strings with enhanced dynamic and bouncing capacities, and in general, enhanced power properties.
- the additives are preferably selected from the group consisting of: slip agents and hydrophobic agents.
- the preferred additives are selected from: erucamide, such as stearyl erucamide, ethylene bis stearamide, polyamide-based polydimethylsiloxane, polyamide-based siloxane with ultra-high molecular mass, fluorine-based polymer, polymer loaded with molybdenum disulfide.
- erucamide such as stearyl erucamide, ethylene bis stearamide, polyamide-based polydimethylsiloxane, polyamide-based siloxane with ultra-high molecular mass, fluorine-based polymer, polymer loaded with molybdenum disulfide.
- the preferred additives are selected from: siloxane-based polymer with ultra-high molecular mass, polydimethylsiloxane-based polymer, silicon dioxide-based compounds, ceramic nanoparticles-based compounds.
- a coating of such additives or other substances can also be applied on the peripheral surface of the sheath, in particular during the manufacture of the strings.
- a coating may be applied onto the outer surface of the sheath.
- Said coating may have non-slip and/or water repelling properties.
- the monofilament string according to the invention has the following properties: a shock-absorbing capacity provided by the core 2, due to its low elasticity;
- the monofilament string shows a good balance between power and control properties, while also having good comfort and durability properties.
- the monofilament string according to the invention also have the following properties due to the presence of graphene or graphane nanoparticles in the sheath: increased rigidity and durability with acceptable lightness, due to the ability of the graphene or graphane nanoparticles to reinforce the structure of the string without severely stiffening said string (due to the nanometric size of the graphene or graphane particles) nor severely weighing said string (due to the low density of the graphene or graphane particles);
- the tested monofilament strings are the same in each of the five following examples. They have the same polyamide structure, but differ from the amount of graphene in the sheath.
- the graphene nanoparticles have a thickness comprised between 1 nm and 2 nm and a lateral dimension comprised between 0.5 and 5 pm.
- the graphene nanoparticles have been provided as a powder which was mixed with the plastic granules fed into the extrusion machine.
- the powder of graphene nanoparticles may be mixed with the polyamide polymer to obtain a compound, and granules made from this compound may then be fed into the extrusion machine.
- the tested monofilament strings are the following:
- a (1 % graphene) - monofilament string comprising:
- a core comprising polyamide 6 and a first copolymer of polyamide 6 and polyamide 6.6
- a sheath comprising a second copolymer of polyamide 6 and polyamide 6.6
- String B (3% graphene) - monofilament string comprising:
- a core comprising polyamide 6 and a first copolymer of polyamide 6 and polyamide 6.6
- a sheath comprising a second copolymer of polyamide 6 and polyamide 6.6
- a core comprising polyamide 6 and a first copolymer of polyamide 6 and polyamide 6.6
- a sheath comprising a second copolymer of polyamide 6 and polyamide 6.6.
- Each monofilament string sample have undergone a hundred cycles of tensile stress of 250 Newton (N) for a duration of 10 minutes: the sample was stretched and relaxed a hundred times. For each cycle, tensile strength, Young’s modulus, tension maintenance, elongation, and plastic deformation of the string have been measured and the mean value over the hundred cycles has been calculated.
- Example 1 influence of graphene on the tensile strength
- TS tensile strength
- the tensile strength of the string is 587 N, which is slightly lower than with 1 % graphene but higher than without graphene.
- Each string sample has undegone a tensile stress (TSS), of an initial value of 250 N, for a duration of 10 minutes.
- TSS tensile stress
- the tensile stress of the string samples naturally decreased as the time passed.
- N the remaining tensile stress applied to each string sample was measured, and corresponds to the tension maintenance of the string, in Newton (N).
- TSS tensile stress
- the tension maintenance influences the durability of the strings and allows for maintaining the mechanical properties of the strings at the same level as they are used.
- Example 4 influence of graphene on the elongation
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- Manufacturing & Machinery (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
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Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19186099 | 2019-07-12 | ||
PCT/EP2020/069572 WO2021009052A1 (en) | 2019-07-12 | 2020-07-10 | Monofilament string for a racket |
Publications (3)
Publication Number | Publication Date |
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EP3997261A1 true EP3997261A1 (en) | 2022-05-18 |
EP3997261C0 EP3997261C0 (en) | 2023-08-30 |
EP3997261B1 EP3997261B1 (en) | 2023-08-30 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP20736738.4A Active EP3997261B1 (en) | 2019-07-12 | 2020-07-10 | Monofilament string for a racket |
Country Status (3)
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EP (1) | EP3997261B1 (en) |
TW (1) | TWI836115B (en) |
WO (1) | WO2021009052A1 (en) |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
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US8713906B2 (en) * | 2006-11-16 | 2014-05-06 | Applied Nanotech Holdings, Inc. | Composite coating for strings |
US20080206559A1 (en) * | 2007-02-26 | 2008-08-28 | Yunjun Li | Lubricant enhanced nanocomposites |
FR2934958B1 (en) | 2008-08-12 | 2012-11-09 | Babolat Vs | ROPE FOR RACKETS, IN PARTICULAR FOR TENNIS RACKETS |
EP2408953A4 (en) * | 2009-03-16 | 2012-09-05 | Ilhan A Aksay | Polymeric fibers and articles made therefrom |
CN106283310A (en) * | 2016-08-30 | 2017-01-04 | 安徽翰文运动用品股份有限公司 | It is exclusively used in the nylon wire of racket |
JP2018187163A (en) * | 2017-05-09 | 2018-11-29 | 株式会社ゴーセン | Racket string and manufacturing method thereof |
ES2776389T3 (en) | 2017-06-21 | 2020-07-30 | Speed France S A S | Monofilament string for a racket and procedure for making said monofilament string |
-
2020
- 2020-07-10 EP EP20736738.4A patent/EP3997261B1/en active Active
- 2020-07-10 WO PCT/EP2020/069572 patent/WO2021009052A1/en unknown
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Also Published As
Publication number | Publication date |
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EP3997261C0 (en) | 2023-08-30 |
TW202116380A (en) | 2021-05-01 |
TWI836115B (en) | 2024-03-21 |
EP3997261B1 (en) | 2023-08-30 |
WO2021009052A1 (en) | 2021-01-21 |
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