A shuttlecock and a method of manufacturing the same

Abstract

The present application relates to the technical field of pickleball racket, and particularly relates to a pickleball racket with a ring-shaped racket core structure and a preparation method thereof, the pickleball racket comprising a racket core and aramid racket faces located on both sides of the racket core; the racket core is a planar concentric ring-shaped composite structure, and sequentially comprises a center foaming layer, an EVA buffer ring layer and a PP honeycomb ring layer from the center to the edge; the center foaming layer is an EPP foaming polypropylene layer or an MPP microporous foaming polypropylene layer; a mechanical interlocking type bonding interface is formed between the EVA buffer ring layer and the PP honeycomb ring layer, and between the EVA buffer ring layer and the center foaming layer. The problems such as poor shock absorption performance, small sweet spot range, easy breakage and collapse, short service life and weak universality in the prior art are solved. The present application realizes integrated upgrading of the structure strength, shock absorption, ball hitting fault tolerance and structure durability of the pickleball racket.

Description

Technical Field

[0001] This invention relates to a Peak racket with a ring-shaped core structure and its manufacturing method, belonging to the field of Peak racket technology. Background Technology

[0002] Peak badminton, as an emerging recreational competitive sport, has rapidly gained popularity in the global and domestic sports markets in recent years due to its low barrier to entry, high entertainment value, and suitability for all age groups, with its audience increasing year by year. At the same time, market demands for Peak rackets' overall performance, user comfort, structural durability, and adaptability to various scenarios are also gradually increasing. The racket core, as the core component of a Peak racket, directly determines the racket's rebound performance, hitting feel, shock absorption, sweet spot range, and product lifespan through its material selection and internal structural design, making it a core indicator for evaluating the quality of Peak rackets.

[0003] Currently, the mainstream Peak racket core structures on the market are mainly divided into two categories: polypropylene (PP) hollow honeycomb cores and one-piece solid foam cores. PP honeycomb cores provide lightweight support through a hexagonal grid structure, offering structural stability and high compressive strength, but they also have significant drawbacks. First, the honeycomb walls are prone to irreversible plastic deformation during long-term high-frequency impacts, leading to racket face collapse or a decrease in local stiffness. Second, vibration transmission is direct upon impact, resulting in a stiff feel, poor shock absorption, and potential arm discomfort with prolonged use. Third, the energy return method is singular, lacking differentiated response capabilities to impacts of varying force. One-piece solid foam cores, represented by polypropylene foam (EPP / MPP), polyurethane foam (PU), and cross-linked polyethylene foam (PE), offer a softer feel, better shock absorption, and lower noise. However, their structural strength and resistance to permanent compression deformation are generally lower than honeycomb materials, making them prone to irreversible compressive deformation after powerful smashes or prolonged use, leading to a decline in elasticity and control. It is evident that both of the aforementioned mainstream structures have inherent flaws and cannot simultaneously meet the diverse usage needs of competitive ball striking, daily leisure, arm protection, and long-term durability. The industry has always faced the technical challenge of performance trade-offs.

[0004] To overcome the limitations of single-material racket cores, some existing technologies attempt to employ multi-layer composite structures. For example, some solutions alternately stack PP honeycomb layers and EVA layers in the thickness direction of the racket face to balance rigidity and cushioning performance; others use a structure where honeycomb plates and shock-absorbing rings are distributed in a ring shape within the racket core plane (e.g., patent publication number CN222488816U). However, these existing composite structures still have significant shortcomings. In multi-layered structures in the thickness direction, the force path of each layer under impact is transmitted vertically, which easily leads to stress concentration at the interface, resulting in a high risk of delamination failure after long-term use; furthermore, the difference in shrinkage rate of different material layers in the thickness direction can easily cause racket warping and deformation, affecting product consistency and service life. In the planar ring-shaped distribution scheme, the central area still uses a honeycomb panel, failing to fundamentally solve the problem of plastic indentation in the central area of ​​the honeycomb material under repeated impacts. Furthermore, the central shock-absorbing ring only serves a single buffering function, lacking a gradient matching design in mechanical properties with the inner and outer layers. The interfacial bonding between layers relies heavily on adhesives, and the problem of interfacial debonding remains prominent under long-term impact loads. In addition, existing composite structures lack performance adjustability, making it impossible to meet the personalized needs of different types of players through simple material replacement.

[0005] In summary, the existing Peak racket core structure still has many shortcomings in terms of shock absorption performance, structural durability, flexibility in adjusting the feel of the shot, and reliability of interlayer bonding. There is an urgent need for a new racket core structure that can integrate the advantages of multiple materials, optimize the internal structural layout, and achieve a synergistic improvement in structural strength and user comfort. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing a Peak racket with a ring-shaped core structure and its manufacturing method, solving problems such as poor shock absorption, small sweet spot, susceptibility to breakage and collapse, short service life, and weak versatility. This invention employs a ring-shaped composite design consisting of an outer rigid support layer, a middle buffer transition layer, and a central functionally adjustable layer. Through material zoning and functional synergy, it achieves an integrated upgrade in Peak racket structural strength, shock absorption, shot tolerance, and structural durability.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a Peak racket with a ring core structure, the Peak racket including a core and aramid racket surfaces located on both sides of the core; the core is a planar concentric ring composite structure, which consists of a central foam layer, an EVA buffer ring layer and a PP honeycomb ring layer from the center to the edge; The central foaming layer is an EPP foamed polypropylene layer or an MPP microporous foamed polypropylene layer. Mechanically interlocking interfaces are formed between the EVA buffer ring layer and the PP honeycomb ring layer, as well as between the EVA buffer ring layer and the central foaming layer.

[0008] Furthermore, the radial width of the PP honeycomb ring layer is 10mm~40mm; The PP honeycomb ring layer has a pore size of 3~10mm and a density of 60kg / m³. 3 ~95kg / m 3 .

[0009] Furthermore, the radial width of the EVA buffer ring layer is 10mm~40mm; The density of the EVA buffer ring layer is 0.080 g / cm³. 3 ~0.20g / cm 3 The Shore C hardness of the EVA buffer ring layer is 20~50.

[0010] Furthermore, the diameter of the central foaming layer is 40mm~160mm; The density of the EPP foamed polypropylene layer is 0.03 g / cm³. 3 ~0.15g / cm 3 The EPP foamed polypropylene layer has a pore size of 0.1~1mm and a pore density of 10. 5 ~10 9 pcs / cm 3 ; The density of the MPP microporous foamed polypropylene layer is 0.04 g / cm³. 3 ~0.15g / cm 3 The MPP microporous foamed polypropylene layer has a pore size of 1~100μm and a pore density of 10. 9 ~10 12 pcs / cm 3 .

[0011] Furthermore, the core thickness is 15±0.3mm, and the thickness of the aramid surface on each side is 0.2mm~0.8mm.

[0012] Furthermore, the core and the aramid surface are bonded together by an adhesive film with a thickness of 0.1mm to 0.2mm.

[0013] This invention also discloses a method for preparing a Peak racket with a ring-shaped core structure, the method being as follows: S1. Die-cutting: Cut the PP honeycomb board, EVA board, central foam board, aramid prepreg and film according to the shape and size required for the racket. S2. Assembly: The cut PP honeycomb ring, EVA buffer ring, and central foam board are assembled in a concentric ring shape in the horizontal plane, so that the EVA buffer ring is located between the PP honeycomb ring and the central foam board, forming a planar ring core structure. Then, the rubber film and aramid prepreg are laid on both sides of the core structure to obtain the assembled racket. S3. Hot pressing: The assembled racket is heated and pressurized to partially melt the EVA buffer ring and allow it to penetrate into the micropores on the surface of the PP honeycomb ring and the central foaming plate, forming a mechanically interlocked interface bond. S4. Edge Sealing: After the racket is heated and pressed, edge sealing strips and grip tape are applied to obtain a Peak racket with a ring core structure.

[0014] Furthermore, the basis weight of the aramid prepreg is 200 g / m². 2 ~240g / m 2 The adhesive content is 38%~45%; The adhesive film is an epoxy adhesive film with a thickness of 0.1mm to 0.2mm.

[0015] Furthermore, in step S3, the hot pressing process conditions are: temperature of 120℃~140℃, pressure of 0.2MPa~0.5MPa, and hot pressing time of 15min~40min.

[0016] Further, in step S3, the hot pressing process involves first preheating at a temperature of 110℃~120℃ and a pressure of 0.1MPa~0.2MPa for 10min~15min; then raising the temperature to 125℃~140℃ and the pressure to 0.3MPa~0.5MPa, and holding the pressure for 15min~25min.

[0017] The beneficial effects of this invention are: The Peak racket described in this invention features a concentric ring-shaped composite structure within the racket core plane. The outer PP honeycomb ring layer provides high-strength structural support and torsional rigidity, ensuring the racket maintains a stable geometric shape during high-speed shots. The middle EVA buffer ring layer efficiently absorbs high-frequency vibrations generated by the shot, reducing the amplitude of vibration transmitted to the handle by 40% to 60% compared to traditional structures, significantly reducing arm fatigue and the risk of sports injuries. The central EPP or MPP foam layer serves as the functional core, providing differentiated elastic feedback and shot feel depending on the material type and density. The three layers work synergistically in the horizontal plane, resulting in excellent performance in terms of rigidity, shock absorption, and resilience.

[0018] In the preparation method described in this invention, the EVA buffer ring is partially melted during hot pressing, allowing it to penetrate into the micropores on the surface of the outer PP honeycomb ring and the central foamed layer. After curing, this forms an "anchor"-like mechanically interlocking interface. This interface bonding mechanism, synergistic with the chemical adhesion of the epoxy film, results in an interlayer bonding strength far exceeding that of traditional methods relying solely on adhesives. Impact testing results show that the embodiments of this invention exhibited no delamination or central depression after 300 high-speed impacts, indicating that this invention effectively solves the technical problem of delamination failure in multi-layer composite structures during long-term use, significantly extending the racket's service life.

[0019] This invention allows for precise adjustment of racket performance by simply changing the material type (EPP or MPP) and density of the central foam layer, without altering the PP honeycomb ring layer and EVA buffer ring layer. The EPP foamed polypropylene layer offers high resilience and excellent energy absorption, providing a soft and stable feel, making it particularly suitable for control-oriented players and beginners. The MPP microporous foamed polypropylene layer boasts high rigidity and excellent compressive strength, delivering direct power feedback and a crisp feel, making it ideal for power players and professional competitions. This adjustable performance mechanism allows manufacturers to use the same molds and most raw materials, adapting to different user groups by simply changing the central layer material, significantly reducing the development cycle and production costs of various product categories.

[0020] More specifically, the preparation method of this invention employs a segmented hot-pressing process. First, preheating and penetration are performed at 110℃~120℃ and 0.1MPa~0.2MPa, allowing the EVA material to fully penetrate the surface micropores of adjacent layers in a moderately softened state, forming a preliminary mechanical interlocking structure. Then, the temperature is increased to 125℃~140℃ and the pressure to 0.3MPa~0.5MPa for high-temperature curing, allowing the epoxy film to fully cross-link and form chemical bonds. Compared to single constant-temperature hot pressing, this segmented process can more precisely control the degree of EVA melt penetration—avoiding both excessive temperature leading to excessive EVA flow and loss, and insufficient temperature preventing effective penetration. Simultaneously, it effectively protects the cell structure of the EPP / MPP foam material from being crushed, ensuring consistent interfacial bonding quality and performance for each batch of products.

[0021] In summary, this invention utilizes a planar concentric annular partitioned structural design to form a three-layer composite system within the racket core's horizontal plane, consisting of a PP honeycomb rigid layer, an EVA buffer transition layer, and an EPP / MPP foam functional layer, arranged sequentially from the outside in. By controlling the partial melting of EVA during hot pressing and its penetration into the micropores of adjacent layers, a mechanically interlocking interface bond is formed after curing, enhancing the interfacial bonding strength between dissimilar material layers. By changing the material type and density of the central foam layer without altering the outer and middle layer structures, different hitting performance characteristics can be achieved. Through impact testing and multiple performance tests including elasticity and rigidity, this invention outperforms existing single-layer homogeneous cores and conventional multi-layer composite cores in terms of shock absorption, structural durability, consistency of hitting feel, and reliability of interfacial bonding, thus meeting the needs of players with different playing styles. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the Peak racket ring core described in this invention; Figure 2 This is a structural diagram of the Peak racket's ring core, with relevant dimensions and positions marked. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0025] A Peak racket with a ring-shaped core structure, the racket comprising a core and aramid facets located on both sides of the core; as shown... Figure 1 As shown, the core is a planar concentric ring composite structure, consisting of a central foaming layer, an EVA buffer ring layer, and a PP honeycomb ring layer from the center to the edge. The central foaming layer is an EPP foamed polypropylene layer or an MPP microporous foamed polypropylene layer. Mechanically interlocking interfaces are formed between the EVA buffer ring layer and the PP honeycomb ring layer, as well as between the EVA buffer ring layer and the central foaming layer.

[0026] Specifically, the mechanically interlocking interface is formed by partially melting EVA material and then penetrating it into the pores near the interface of the PP honeycomb ring layer and into the surface micropores near the interface of the central foaming layer, and then curing it.

[0027] Specifically, the outer PP honeycomb ring layer: The outer skeleton of the racket core is constructed using polypropylene (PP) honeycomb, providing overall structural rigidity and torsional strength. It withstands the tensile and compressive loads transmitted by the racket face during impact, providing high bending and torsional stiffness to resist large deformations at the moment of impact, ensuring that the racket does not undergo overall bending deformation or twisting during long-term use. The handle of the Peak racket also uses PP honeycomb material.

[0028] More specifically, the radial width of the PP honeycomb ring layer is 10mm~40mm (i.e., the ring width of the ring structure, such as...). Figure 2 (D1 in the racket, excluding the handle). The PP honeycomb ring layer has a pore size of 3~10mm and a density of 60kg / m³. 3 ~95kg / m 3 .

[0029] Preferably, the radial width of the PP honeycomb ring layer is 20mm~30mm.

[0030] Preferably, the PP honeycomb ring layer has a pore size of 4-6 mm and a density of 70 kg / m³. 3 ~85kg / m 3 .

[0031] Specifically, the intermediate EVA buffer ring layer uses ethylene-vinyl acetate copolymer (EVA) foam material, which can be a closed-cell or open-cell foam structure. As a transitional medium between the PP honeycomb ring layer and the central functional core layer, the EVA buffer ring layer mainly performs two functions: first, it absorbs and disperses the impact energy of the ball, reducing the vibration transmitted to the arm and improving the comfort of hitting the ball; second, it provides flexible support when the central functional core layer is compressed and deformed, avoiding stress concentration between the rigid honeycomb and the central hard material, and preventing interface debonding or local crushing.

[0032] More specifically, the radial width of the EVA buffer ring layer is 10mm~40mm; The density of the EVA buffer ring layer is 0.080 g / cm³. 3 ~0.20g / cm 3 The Shore C hardness of the EVA buffer ring layer is 20~50.

[0033] Preferably, the radial width of the EVA buffer ring layer is 20mm~30mm (i.e., the ring width of the ring structure, such as...). Figure 2 (D2 in the middle) Preferably, the density of the EVA buffer ring layer is 0.08 g / cm³. 3 ~0.15g / cm 3The Shore C hardness of the EVA buffer ring layer is 30~40.

[0034] Specifically, the lateral diameter of the central foaming layer is 40mm~160mm (e.g., Figure 2 D3 in ).

[0035] Preferably, the transverse diameter of the central foam layer is 80mm to 120mm.

[0036] EPP (Expanded polypropylene) is a type of foamed polypropylene with a honeycomb-like microporous structure. It has relatively large pore sizes and a low cell density, and is foamed using traditional physical steam foaming. The material is lightweight and elastic. MPP (Microcellular Polypropylene Foam) is a type of microcellular foamed polypropylene, prepared using a supercritical fluid (CO2 or N2) foaming process. It has a closed-cell structure, extremely high cell density, uniform distribution, and is continuous and homogeneous throughout. The high cell density and uniform distribution are the structural basis for MPP's excellent mechanical properties.

[0037] Specifically, the density of the EPP foamed polypropylene layer is 0.03 g / cm³. 3 ~0.15g / cm 3 The EPP foamed polypropylene layer has a pore size of 0.1~1mm and a pore density of 10. 5 ~10 9 pcs / cm 3 .

[0038] Preferably, the density of the EPP foamed polypropylene layer is 0.05 g / cm³. 3 ~0.1g / cm 3 .

[0039] Specifically, the density of the MPP microporous foamed polypropylene layer is 0.04 g / cm³. 3 ~0.15g / cm 3 The MPP microporous foamed polypropylene layer has a pore size of 1~100μm and a pore density of 10. 9 ~10 12 pcs / cm 3 .

[0040] Preferably, the density of the MPP microporous foamed polypropylene layer is 0.06 g / cm³. 3 ~0.1g / cm 3 .

[0041] Specifically, the core thickness is 15±0.3mm, the central foam layer, EVA buffer ring layer and PP honeycomb ring layer have the same thickness, and the thickness of the aramid surface on each side is 0.2mm~0.8mm.

[0042] Specifically, the aramid racket face uses aramid prepreg (a prepreg made by impregnating aramid fibers with epoxy resin), which has high strength, high abrasion resistance and excellent impact toughness, protects the internal racket core structure, and directly participates in the friction of hitting the ball, affecting the spin performance of the ball.

[0043] Specifically, the racket core and the aramid racket surface are bonded together by an adhesive film with a thickness of 0.1mm to 0.2mm.

[0044] This invention also discloses a method for preparing a Peak racket with a ring-shaped core structure, the method being as follows: S1. Die-cutting: Cut the PP honeycomb board, EVA board, central foam board, aramid prepreg and film according to the shape and size required for the racket. S2. Assembly: The cut PP honeycomb ring, EVA buffer ring, and central foam board are assembled in a concentric ring shape in the horizontal plane, so that the EVA buffer ring is located between the PP honeycomb ring and the central foam board, forming a planar ring core structure. Then, the rubber film and aramid prepreg are laid on both sides of the core structure to obtain the assembled racket. S3. Hot pressing: The assembled racket is heated and pressurized to partially melt the EVA buffer ring and allow it to penetrate into the micropores on the surface of the PP honeycomb ring and the central foaming plate, forming a mechanically interlocked interface bond. S4. Edge Sealing: After the racket has been heated and pressed, burrs and rough edges are removed, the edges are trimmed neatly, and edge sealing strips and grip tape are applied to obtain a Peak racket with a complete ring-shaped core.

[0045] Specifically, the basis weight of the aramid prepreg fabric is 200 g / m². 2 ~240g / m 2 The adhesive content is 38%~45%; The adhesive film is an epoxy adhesive film with a thickness of 0.1mm to 0.2mm.

[0046] Specifically, in step S3, the hot pressing process conditions are: temperature of 120℃~140℃, pressure of 0.2MPa~0.5MPa, and hot pressing time of 15min~40min.

[0047] Specifically, in step S3, the hot pressing process involves preheating at a temperature of 110℃~120℃ and a pressure of 0.1MPa~0.2MPa for 10min~15min; then raising the temperature to 125℃~140℃ and the pressure to 0.3MPa~0.5MPa, and holding the pressure for 15min~25min.

[0048] The present invention will be further described in detail below with reference to embodiments and comparative examples, but the implementation of the present invention is not limited thereto. All raw materials used in the embodiments are commercially available products, and the types and sources of each raw material are as follows: The PP honeycomb core is produced by Zhejiang Haozhuo New Material Technology Co., Ltd., with a pore size of 6mm and no non-woven fabric on the surface. The model number is PP06-85. The MPP board is an M-PP microporous foamed polypropylene board produced by Suzhou Shensai New Material Co., Ltd., model M-PP15. The EPP board is an EPP foam board produced by Wuxi Huitong Lightweight Materials Co., Ltd., model QB15P. The EVA board is EVA foam-P045 produced by Changzhou Hanchang Buffer Material Co., Ltd., with a density of 105kg / m³ and a Shore C hardness of 40. The aramid prepreg fabric is a para-aramid twill prepreg fabric produced by Taihe New Materials Group Co., Ltd., with a basis weight of 220 g / m². 2 It contains 38%~45% glue and is model THPC7292. The film is J313T epoxy film produced by Weihai Guangxuan New Materials Co., Ltd., with a thickness of 0.2mm, white color, toughness, and release paper on both sides.

[0049] Example 1: Preparation of Peak racket.

[0050] This embodiment provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0051] The core structure consists of a PP honeycomb ring layer, an EVA buffer ring layer, and an MPP central layer.

[0052] The PP honeycomb annular layer has a transverse outer diameter of 200mm, a transverse inner diameter of 160mm, a radial width of 20mm for the annular region, a honeycomb pore size of 6mm, and a density of 85kg / m³. 3 ; The EVA buffer ring layer has a transverse outer diameter of 160 mm, a transverse inner diameter of 120 mm, a radial width of 20 mm for the ring-shaped region, and a density of 0.10 g / cm³. 3 Its Shore C hardness is 40; The central MPP layer has a lateral diameter of 120 mm and a density of 0.06 g / cm³. 3 The pore size is 1~100μm, and the pore density is 10. 9 ~10 12 pcs / cm 3 .

[0053] Each layer in the core is 15mm thick.

[0054] The adhesive film is J313T epoxy film with a thickness of 0.2mm; The aramid prepreg fabric has a basis weight of 220 g / m². 2 .

[0055] The preparation method is as follows: (1) Die-cutting: Cut the PP honeycomb board, EVA board, MPP board, aramid prepreg and film according to the above dimensions.

[0056] (2) Assembly: The cut PP honeycomb ring layer, EVA buffer ring layer and MPP center layer are assembled in a concentric ring shape in the horizontal plane, so that the EVA buffer ring layer is located between the PP honeycomb ring layer and the MPP center layer to form a planar ring core structure. Then, the adhesive film and aramid prepreg are laid on both sides of the core structure and placed into the mold.

[0057] (3) Hot pressing: Transfer the mold to a flat hot press. The hot pressing temperature is 120℃, the pressure is 0.3MPa, and the holding time is 20min.

[0058] (4) Edge sealing: Take out the racket after hot pressing, remove burrs and rough edges, trim the edges neatly, and then attach edge sealing strips and grip tape to obtain a Peak racket with a ring core structure.

[0059] Example 2: Preparation of Peak racket.

[0060] This embodiment provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0061] The core structure consists of a PP honeycomb ring layer, an EVA buffer ring layer, and an EPP center layer.

[0062] The PP honeycomb annular layer has a transverse outer diameter of 200mm, a transverse inner diameter of 160mm, a radial width of 20mm for the annular region, a honeycomb pore size of 6mm, and a density of 85kg / m³. 3 ; The EVA buffer ring layer has a transverse outer diameter of 160 mm, a transverse inner diameter of 120 mm, a radial width of 20 mm for the ring-shaped region, and a density of 0.10 g / cm³. 3 Its Shore C hardness is 40; The central EPP layer has a lateral diameter of 120 mm and a density of 0.05 g / cm³. 3 The pore size is 0.1~1mm, and the pore density is 10. 5 ~10 9 pcs / cm 3 .

[0063] Each layer is 15mm thick. The specifications of the adhesive film and aramid prepreg are the same as in Example 1.

[0064] The preparation method is as follows: (1) Die-cutting: Cut the PP honeycomb board, EVA board, EPP board, aramid prepreg and film according to the above dimensions.

[0065] (2) Assembly: The cut PP honeycomb ring layer, EVA buffer ring layer and EPP center layer are assembled in a concentric ring shape in the horizontal plane, so that the EVA buffer ring layer is located between the PP honeycomb ring layer and the EPP center layer to form a planar ring core structure. Then, the adhesive film and aramid prepreg are laid on both sides of the core structure and placed into the mold.

[0066] (3) Hot pressing: Transfer the mold to a flat hot press. The hot pressing temperature is 120℃, the pressure is 0.3MPa, and the holding time is 20min.

[0067] (4) Edge sealing: Take out the racket after hot pressing, remove burrs and rough edges, trim the edges neatly, and then attach edge sealing strips and grip tape to obtain a Peak racket with a ring core structure.

[0068] Example 3: Preparation of Peak racket.

[0069] This embodiment provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0070] The core structure consists of a PP honeycomb ring layer, an EVA buffer ring layer, and an EPP center layer.

[0071] The PP honeycomb annular layer has a transverse outer diameter of 200mm, a transverse inner diameter of 180mm, a radial width of 10mm for the annular region, a honeycomb pore size of 6mm, and a density of 85kg / m³. 3 ; The EVA buffer ring layer has a transverse outer diameter of 180 mm, a transverse inner diameter of 160 mm, a radial width of 10 mm for the ring-shaped region, and a density of 0.10 g / cm³. 3 Its Shore C hardness is 40; The central EPP layer has a lateral diameter of 160 mm and a density of 0.05 g / cm³. 3 The pore size is 0.1~1mm, and the pore density is 10. 5 ~10 9 pcs / cm 3 Each layer is 15mm thick.

[0072] The specifications of the adhesive film and aramid prepreg are the same as in Example 1.

[0073] The preparation method is as follows: (1) Die-cutting: Cut the PP honeycomb board, EVA board, EPP board, aramid prepreg and film according to the above dimensions.

[0074] (2) Assembly: The cut PP honeycomb ring layer, EVA buffer ring layer and EPP center layer are assembled in a concentric ring shape in the horizontal plane, so that the EVA buffer ring is located between the PP honeycomb ring and the EPP center layer, forming a planar ring core structure. Then, the adhesive film and aramid prepreg are laid on both sides of the core structure and placed into the mold.

[0075] (3) Hot pressing: Transfer the mold to a flat hot press. The hot pressing temperature is 120℃, the pressure is 0.3MPa, and the holding time is 20min.

[0076] (4) Edge sealing: Take out the racket after hot pressing, remove burrs and rough edges, trim the edges neatly, and then attach edge sealing strips and grip tape to obtain a Peak racket with a ring core structure.

[0077] Example 4: Preparation of Peak racket.

[0078] This embodiment provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0079] The same raw materials as in Example 1 were used. The only difference was the use of a segmented hot-pressing process during preparation. The specific preparation method is as follows: (1) Die-cutting: Cut the PP honeycomb board, EVA board, MPP board, aramid prepreg and film according to the above dimensions.

[0080] (2) Assembly: The cut PP honeycomb ring layer, EVA buffer ring layer and MPP center layer are assembled in a concentric ring shape in the horizontal plane, so that the EVA buffer ring is located between the PP honeycomb ring and the MPP center layer to form a planar ring core structure. Then, the adhesive film and aramid prepreg are laid on both sides of the core structure and placed into the mold.

[0081] (3) Hot pressing: Transfer the mold to a flat hot press, preheat and penetrate for 12 minutes at a temperature of 115℃ and a pressure of 0.15MPa, then raise the temperature to 135℃ and the pressure to 0.4MPa, and hold the pressure for 20 minutes to cure.

[0082] (4) Edge sealing: Take out the racket after hot pressing, remove burrs and rough edges, trim the edges neatly, and then attach edge sealing strips and grip tape to obtain a Peak racket with a ring core structure.

[0083] Example 5: Preparation of Peak racket.

[0084] This embodiment provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0085] The same raw materials as in Example 2 were used. The only difference was the use of a segmented hot-pressing process during preparation. The specific preparation method is as follows: (1) Die-cutting: Cut the PP honeycomb board, EVA board, EPP board, aramid prepreg and film according to the above dimensions.

[0086] (2) Assembly: The cut PP honeycomb ring layer, EVA buffer ring layer and EPP center layer are assembled in a concentric ring shape in the horizontal plane, so that the EVA buffer ring is located between the PP honeycomb ring and the EPP center layer, forming a planar ring core structure. Then, the adhesive film and aramid prepreg are laid on both sides of the core structure and placed into the mold.

[0087] (3) Hot pressing: Transfer the mold to a flat hot press, preheat and penetrate for 15 minutes at a temperature of 110℃ and a pressure of 0.1MPa, then raise the temperature to 125℃ and the pressure to 0.3MPa, and hold the pressure for 25 minutes to cure.

[0088] (4) Edge sealing: Take out the racket after hot pressing, remove burrs and rough edges, trim the edges neatly, and then attach edge sealing strips and grip tape to obtain a Peak racket with a ring core structure.

[0089] Comparative Example 1: Preparation of a Peak racket.

[0090] This comparative example provides a Peak racket with a single-layer PP honeycomb core.

[0091] The core is a single-layer PP honeycomb board with a thickness of 15mm, a honeycomb pore size of 6mm, and a density of 85kg / m³. The specifications of the adhesive film and aramid prepreg are the same as in Example 1.

[0092] The preparation method is as follows: After bonding the PP honeycomb panel to the aramid prepreg fabric on both sides with adhesive film, the panel is placed in a mold. The mold is then transferred to a flatbed hot press, where the hot pressing temperature is 120℃, the pressure is 0.3MPa, and the time is 20 minutes. After hot pressing, the racket is removed, the rough edges are trimmed, and edge sealing strips and grip tape are applied to seal the edges, resulting in a Peak racket with a single-layer PP honeycomb core.

[0093] Comparative Example 2: Preparation of a Peak racket.

[0094] This comparative example provides a Peak racket with a single-layer aramid honeycomb core.

[0095] The core material is a single-layer meta-aramid honeycomb board (manufacturer: Jiangsu Hongzan Honeycomb Technology Co., Ltd., model: 1313-5.5-48), with a thickness of 15mm and a honeycomb cell side length of 5.5mm. The specifications of the adhesive film and aramid prepreg are the same as in Example 1.

[0096] The preparation method is as follows: After bonding the meta-aramid honeycomb plate to the aramid prepreg fabrics on both sides with adhesive film, the plate is placed in a mold. The mold is then transferred to a flatbed hot press, where the hot pressing temperature is 120℃, the pressure is 0.3MPa, and the time is 20 minutes. After the hot pressing is completed, the racket is removed, the rough edges are trimmed, and edge sealing strips and grip tape are applied to seal the edges, resulting in a Peak racket with a single meta-aramid honeycomb plate core.

[0097] Comparative Example 3: Preparation of a Peak racket.

[0098] This comparative example provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0099] In Comparative Example 3, the outer diameter of the EVA buffer ring layer is 160 mm, the inner diameter is 150 mm, and the radial width of the annular region is 5 mm; the diameter of the central MPP layer is 150 mm, which reduces the radial width of the annular region of the EVA buffer ring layer. Other raw materials and preparation processes are the same as in Example 1.

[0100] Comparative Example 4: Preparation of a Peak racket.

[0101] This comparative example provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0102] In Comparative Example 4, the outer diameter of the EVA buffer ring layer is 160 mm, the inner diameter is 70 mm, and the radial width of the annular region is 45 mm; the diameter of the central MPP layer is 70 mm, which increases the radial width of the annular region of the EVA buffer ring layer. Other raw materials and preparation processes are the same as in Example 1.

[0103] Comparative Example 5: Preparation of a Peak racket.

[0104] This comparative example provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0105] The Peak racket was prepared using the same principle and process as in Example 1, except that the Shore C hardness of the EVA buffer ring layer used in Comparative Example 5 was 25 (manufacturer: Changzhou Hanchang Buffer Material Co., Ltd., model E050), and all other process conditions were the same as in Example 1.

[0106] Comparative Example 6: Preparation of a Peak racket.

[0107] This comparative example provides a Peak racket with a ring-shaped core structure and its manufacturing method.

[0108] The Peak racket was prepared using the same principle and process as in Example 1, except that the Shore C hardness of the EVA buffer ring layer used in Comparative Example 6 was 60 (manufacturer: Dongguan Yihengxin Plastic Materials Co., Ltd., model: YXHA-60), and all other process conditions were the same as in Example 1.

[0109] The performance of the Peak rackets obtained from the above embodiments and comparative examples was tested. The specific test results are shown in Table 1 below, and the test methods involved are as follows.

[0110] Peak rackets underwent the following performance tests: (1) Shelling verification: Refer to T / WQTB 1005-2024 standard to simulate the durability of rackets under actual use conditions. Use tennis balls weighing 56~58g, with a speed of 100~110km / h when the tennis ball reaches the racket face, a service point 1.5~2m away from the racket face, and shelling 300 times. Observe whether the racket shows delamination and whether the center of the racket face is dented.

[0111] (2) Rebound Coefficient (PBCoR): Referencing the UPA-A and USAPA racket certification standards, the ball is launched from an air cannon and impacts the racket face with an incident velocity of 96.5 km / h and an incident angle perpendicular to the racket face. The ratio of the rebound velocity to the incident velocity is calculated using high-speed video.

[0112] (3) Maximum racket efficiency coefficient (PEF): The test method is the same as that for the bounce coefficient, with an incident velocity of 80.5 km / h.

[0113] (4) Deformation: Test the deformation of the racket face under specific pressure to characterize the racket's flexibility.

[0114] (5) Average deflection force (ADF): The static deflection force that resists bending when pressure is applied to the racket face, which characterizes the racket rigidity.

[0115] Table 1 Peak racket performance test data

[0116] As can be seen from the data in the table above, the Peak rackets prepared using the method described in this invention in Examples 1-5 did not exhibit delamination after 300 high-speed hits, and the center of the racket face showed no indentation. The hit verification results were superior to Comparative Examples 1 and 2. The PBCoR (rebound coefficient) and PEF (maximum racket efficiency coefficient) values ​​of Examples 1-5 were higher than those of Comparative Example 2, and not lower than, or even slightly higher than, those of Comparative Example 1. This indicates that the ring-shaped core structure of this invention, while maintaining good elastic energy feedback, has significantly better structural durability than single-layer PP honeycomb cores and single-layer aramid honeycomb cores. The ADF (average deflection force) values ​​of Examples 1-5 were comparable to or slightly higher than those of Comparative Example 1, and the deformation was comparable to that of Comparative Example 1, indicating that the bending stiffness of the rackets of this invention is at the same level as that of rigid PP honeycomb cores, providing stable rigid support for hitting the ball. At the same time, the efficient shock absorption of the EVA buffer ring layer effectively absorbed the high-frequency vibrations generated by the hit, resulting in significantly better user comfort than Comparative Example 1.

[0117] Furthermore, the experimental results of Examples 4 and 5 show that when the hot pressing process uses a segmented hot pressing technique, the PBCoR values ​​of Examples 4 and 5 are higher than those of Examples 1 and 2, which use a constant temperature and pressure process. This indicates that segmented hot pressing, by allowing the EVA material to fully soften and penetrate into the micropores of adjacent layers at a lower temperature, followed by epoxy resin curing at a higher temperature, enables a more complete formation of the mechanical interlocking interface, resulting in higher interface bonding quality and less loss of elastic energy transfer, thereby further optimizing the elastic feedback performance of the racket. In terms of shelling verification, Examples 4 and 5, like Examples 1-3, showed no delamination or dents; in terms of deformation, Examples 4 and 5 were comparable to their corresponding Examples 1 and 2. It is evident that the segmented hot pressing process, while ensuring structural durability, provides more stable interface bonding quality, making it particularly suitable for production scenarios with high requirements for product consistency and reliability.

[0118] A comparison of the experimental results of Comparative Example 1 and Examples 1-5 shows that: Comparative Example 1, using a single-layer PP honeycomb core, did not show delamination after impact, but a significant indentation appeared in the center of the racket face. This indicates that the honeycomb walls underwent irreversible plastic deformation under repeated impacts. With prolonged use, this indentation will further worsen, ultimately leading to racket performance degradation or even failure. In contrast, Examples 1-5 of this invention, due to the excellent toughness and elastic recovery of the central EPP / MPP foam layer, can quickly recover its deformation after impact. Combined with the flexible support of the EVA buffer ring layer and the circumferential constraint of the PP honeycomb ring layer, the synergistic effect of the three layers effectively suppresses the accumulation of plastic deformation in the central region, resulting in no indentation in the center of the racket face after impact. This result demonstrates that the present invention is significantly superior to the traditional single-layer honeycomb core in terms of long-term durability.

[0119] A comparison of the experimental results of Comparative Example 2 and Examples 1-5 shows that Comparative Example 2, which uses a single-layer meta-aramid honeycomb core, exhibited delamination after impact, indicating that the interfacial bonding strength between the aramid honeycomb and the aramid surface was insufficient to resist high-frequency impact loads. In contrast, in Examples 1-5 of this invention, the EVA buffer ring layer partially melted during hot pressing and penetrated into the micropores on the edges of the PP honeycomb ring layer and the surface of the central foam layer. After curing, it formed an anchor-type mechanical interlocking interface. Combined with the chemical bonding of the epoxy film, this achieved an interfacial bonding strength far exceeding that of simple adhesive solutions, and no delamination was observed after impact.

[0120] A comparison of the experimental results of Comparative Example 3 and Example 1 shows that the radial width of the EVA buffer ring layer in Comparative Example 3 is only 5mm, which is smaller than the 10mm~40mm range specified in this invention. The smaller ring width results in a smaller buffering effect of EVA, less recoverable elasticity of the racket, a depression in the center of the racket after a shot, and lower PBCoR and PEF, resulting in less deformation. Furthermore, the overall feel of the racket is stiffer and the vibration is stronger.

[0121] A comparison of the experimental results of Comparative Example 4 and Example 1 shows that the radial width of the EVA buffer ring layer in Comparative Example 4 is 45mm, which is larger than the 10mm~40mm range specified in this invention. The excessively wide EVA ring compresses the diameter of the central MPP layer to 70mm, significantly reducing the sweet spot area and affecting the racket's hitting performance. Simultaneously, the excessively high EVA content reduces the overall rigidity of the racket core. After impact testing, the racket center shows a depression, and the ADF value is significantly lower than in Example 1, indicating increased deformation and a softer feel, failing to meet the rigid support requirements of power players.

[0122] A comparison of the experimental results of Comparative Example 5 and Example 1 shows that: the Shore C hardness of the EVA buffer ring layer in Comparative Example 5 is less than 20, indicating that the EVA material is too soft. Under hot pressing temperature, it softens excessively and even melts and flows, with a large amount of EVA material being squeezed out of the annular area under pressure, failing to effectively remain at the interface and form a mechanical interlock. Simultaneously, the excessively flowing EVA also contaminates adjacent interfaces, affecting the adhesion of the epoxy film and causing racket delamination after impact. Furthermore, the softer EVA buffer layer has poor support, a larger deformation than in Example 1, a lower rebound coefficient, and a softer feel when hitting the ball.

[0123] A comparison of the experimental results of Comparative Example 6 and Example 1 shows that the Shore C hardness of the EVA buffer ring layer in Comparative Example 6 is higher than 50. The EVA material is too hard and cannot generate sufficient creep deformation at the hot-pressing temperature to penetrate into the micropores on the edge and center layer surface of the PP honeycomb grid. The mechanical interlocking effect is weak, and the interfacial bonding mainly relies on the chemical adhesion of the epoxy film, resulting in insufficient impact peeling resistance. Therefore, Comparative Example 6 also showed delamination after shelling.

[0124] In summary, the annular structure of the PP honeycomb ring layer, EVA buffer ring layer, and central foam layer defined by this invention, along with the selection of relevant material dimensions and the coordination of manufacturing process conditions, enables Peak rackets to simultaneously achieve excellent elastic feedback performance, structural fatigue resistance, and interfacial bonding durability. This provides Peak rackets with a core solution that combines high strength, high shock absorption, and high durability.

[0125] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0126] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A Peak racket with a ring-shaped core structure, characterized in that, The Peak racket includes a core and aramid surfaces on both sides of the core; the core is a planar concentric ring composite structure, consisting of a central foam layer, an EVA buffer ring layer, and a PP honeycomb ring layer from the center to the edge. The central foaming layer is an EPP foamed polypropylene layer or an MPP microporous foamed polypropylene layer. Mechanically interlocking interfaces are formed between the EVA buffer ring layer and the PP honeycomb ring layer, as well as between the EVA buffer ring layer and the central foaming layer.

2. The Peak racket with a ring-shaped core structure according to claim 1, characterized in that, The radial width of the PP honeycomb ring layer is 10mm~40mm; The PP honeycomb ring layer has a pore size of 3~10mm and a density of 60kg / m³. 3 ~95kg / m 3 .

3. The Peak racket with a ring-shaped core structure according to claim 1, characterized in that, The radial width of the EVA buffer ring layer is 10mm~40mm; The density of the EVA buffer ring layer is 0.08 g / cm³. 3 ~0.20g / cm 3 The Shore C hardness of the EVA buffer ring layer is 20~50.

4. The Peak racket with a ring-shaped core structure according to claim 1, characterized in that, The transverse diameter of the central foaming layer is 40mm~160mm; The density of the EPP foamed polypropylene layer is 0.03 g / cm³. 3 ~0.15g / cm 3 The EPP foamed polypropylene layer has a pore size of 0.1~1mm and a pore density of 10. 5 ~10 9 pcs / cm 3 ; The density of the MPP microporous foamed polypropylene layer is 0.04 g / cm³. 3 ~0.15g / cm 3 The MPP microporous foamed polypropylene layer has a pore size of 1~100μm and a pore density of 10. 9 ~10 12 pcs / cm 3 .

5. The Peak racket with a ring-shaped core structure according to claim 1, characterized in that, The core thickness is 15±0.3mm, and the thickness of the aramid surface on each side is 0.2mm~0.8mm.

6. The Peak racket with a ring-shaped core structure according to claim 1, characterized in that, The racket core and the aramid racket surface are bonded together by an adhesive film with a thickness of 0.1mm to 0.2mm.

7. A method for manufacturing a Peak racket with a ring-shaped core structure according to any one of claims 1-6, characterized in that, The preparation method is as follows: S1. Die-cutting: Cut the PP honeycomb board, EVA board, central foam board, aramid prepreg and film according to the shape and size required for the racket. S2. Assembly: The cut PP honeycomb ring, EVA buffer ring, and central foam board are assembled in a concentric ring shape in the horizontal plane, so that the EVA buffer ring is located between the PP honeycomb ring and the central foam board, forming a planar ring core structure. Then, the rubber film and aramid prepreg are laid on both sides of the core structure to obtain the assembled racket. S3. Hot pressing: The assembled racket is heated and pressurized to partially melt the EVA buffer ring and allow it to penetrate into the micropores on the surface of the PP honeycomb ring and the central foaming plate, forming a mechanically interlocked interface bond. S4. Edge Sealing: After the racket is heated and pressed, edge sealing strips and grip tape are applied to obtain a Peak racket with a ring core structure.

8. The method for manufacturing a Peak racket with a ring-shaped core structure according to claim 7, characterized in that, The aramid prepreg fabric has a basis weight of 200 g / m². 2 ~240g / m 2 The adhesive content is 38%~45%; The adhesive film is an epoxy adhesive film with a thickness of 0.1mm to 0.2mm.

9. The method for manufacturing a Peak racket with a ring-shaped core structure according to claim 7, characterized in that, In step S3, the hot pressing process conditions are: temperature 120℃~140℃, pressure 0.2MPa~0.5MPa, and hot pressing time 15min~40min.

10. The method for manufacturing a Peak racket with a ring-shaped core structure according to claim 7, characterized in that, In step S3, the hot pressing process involves preheating at a temperature of 110℃~120℃ and a pressure of 0.1MPa~0.2MPa for 10min~15min; then raising the temperature to 125℃~140℃ and the pressure to 0.3MPa~0.5MPa, and holding the pressure for 15min~25min.

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