A racket

Abstract

This invention relates to the field of racket technology and discloses a racket. The racket blade of this invention includes an inner core layer, a first surface layer, and a second surface layer; the inner core layer is made of an elastomeric plastic through a foaming process; the elastomeric plastic is a modified foamed TPU material, which includes the following raw materials in parts by weight: 40-60 parts thermoplastic polyurethane, 15-25 parts EVA, 10-20 parts polyolefin elastomer, 3-6 parts POE-g-MAH, 3-8 parts reinforcing agent, 0.2-0.5 parts zinc stearate, and 0.2-0.5 parts antioxidant; this material has excellent resilience, wear resistance, and mechanical properties, and its application in the inner core layer of Peak rackets has good application prospects.

Description

Technical Field

[0001] This invention relates to the field of racket technology, specifically to an inner core material for rackets. Background Technology

[0002] Peak rackets typically consist of a blade (including the core, outer layer, and edge strips) and a handle. The core material is the key component determining the racket's feel, control accuracy, shock absorption, and durability. Currently, most Peak rackets on the market use polypropylene honeycomb structures or conventional foam materials (such as EPP and EVA) for their cores. For example, polypropylene honeycomb cores are widely used due to their lightweight and elasticity, but they are prone to "core collapse," which directly weakens the racket's spring force and shortens its lifespan.

[0003] To overcome the aforementioned defects of honeycomb core layers, foamed material cores have gradually become an important research and development direction for Peak rackets in recent years. Foamed material cores replace the hollow structure of honeycomb with a continuous and uniform microporous structure, fundamentally eliminating the risk of structural collapse caused by honeycomb wall buckling, and offering significant shock absorption and noise reduction advantages. However, existing foamed core materials still face many performance bottlenecks. Firstly, the energy rebound rate of conventional EVA foam materials is typically between 40% and 60%, reaching its technical limit and failing to meet the demands of high-level athletes for extreme energy return; EPP foam core layers inherently suffer from insufficient buffering and energy absorption performance. Therefore, developing a new type of Peak racket core material that combines high resilience, excellent mechanical properties, and controllable processing dimensions has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention provides an inner core material for a racket, the inner core material being used in Peak rackets.

[0005] The objective of this invention can be achieved through the following technical solutions: A racket includes a racket blade and a handle, wherein the racket blade includes an inner core layer, a first surface layer, and a second surface layer; The inner core layer is made of elastomeric plastic through a foaming process; The first and second surface layers are made of the same material, carbon fiber composite thermoplastic polyurethane.

[0006] The racket also includes a binding strip, which is used to seal the sides of the racket. The edge banding strip is a TPU edge banding strip, and the edges are sealed using a hot pressing process.

[0007] The elastomeric plastic is a modified foamed TPU material, comprising the following raw materials in parts by weight: 40-60 parts thermoplastic polyurethane, 15-25 parts EVA, 10-20 parts polyolefin elastomer, 3-6 parts POE-g-MAH, 3-8 parts reinforcing agent, 0.2-0.5 parts zinc stearate, and 0.2-0.5 parts antioxidant.

[0008] The reinforcing agent is prepared by grafting double bonds onto the surface of mesoporous silica as a core, and then copolymerizing styrene, a modifier, long-chain alkane acrylate, and ethylene on the silica surface using a free radical polymerization reaction; the modifier is prepared by reacting polyethylene glycol monomethyl ether-350 and 4-vinylphenylboronic acid.

[0009] Further, the reinforcing agent is prepared by the following steps: Step A1: Add polyethylene glycol monomethyl ether-350 and 4-vinylphenylboronic acid to toluene, mix and stir evenly, heat to 110℃, reflux at a constant temperature for 6.5-8.5h, remove water and toluene by azeotropic reaction, and dry to obtain the modifier. Furthermore, in step A1, the molar ratio of polyethylene glycol monomethyl ether-350 and 4-vinylphenylboronic acid is 2:1; Step A2: Add mesoporous silica to excess ethanol and reflux for 30 min, then add KH570 and deionized water, maintain reflux at 50-60℃ for 6 h, filter, wash and dry to obtain modified silica. Further, in step A2, the ratio of mesoporous silica, ethanol, KH570 and deionized water is 2g:80-120mL:0.5-1mL:8-15mL; Step A3: Disperse the modified silica evenly in toluene by ultrasonication, then add a mixture of styrene, modifier and long-chain alkane acrylate and stir evenly. Then add benzoyl peroxide and stir evenly. Purge with nitrogen and heat to 80°C and stir for 20-24 hours. Centrifuge, filter, wash with anhydrous toluene and dry to obtain the reinforcing agent. Further, in step A3, the ratio of modified silica, toluene, styrene, modifier, long-chain alkane acrylate, and benzoyl peroxide is 1g:100mL:0.2-0.4mol:0.05-0.08mol:0.02-0.04mol:0.4-0.6g; Further, the long-chain alkane of acrylate mentioned in step A3 is one of lauryl acrylate, tetradecyl acrylate, or docosyl acrylate.

[0010] The preparation method of the modified foamed TPU material includes the following steps: Step S1: Add thermoplastic polyurethane, EVA, polyolefin elastomer, POE-g-MAH, reinforcing agent, zinc stearate and antioxidant to a mixer and stir evenly. Then feed the mixture into a twin-screw extruder and extrude and granulate it at 170-180℃ to obtain blended granules. Step S2: Add the blended particles into the autoclave, introduce carbon dioxide for foaming treatment, release the pressure of the autoclave within 2-3 seconds, and obtain the modified foamed TPU material. Furthermore, the foaming conditions in step S2 are: pressure of 80-150 bar, temperature of 125-135℃, and foaming time of 1-3 hours.

[0011] The method for manufacturing the racket includes the following steps: Step 1: Heat thermoplastic polyurethane to 120-130℃ and then pre-impregnate it onto carbon fiber woven fabric to obtain the first and second surface layers. Step 2: The modified foamed TPU material is steam molded into an inner core layer board, thus obtaining the inner core layer. Step 3: Place the first surface layer, inner core layer, second surface layer, and side TPU edging strip in the mold in sequence, and hot press them at 150-160℃ and 0.3-0.6 MPa. After cooling, cut them to obtain the racket plate, and then install the handle to obtain the racket.

[0012] The beneficial effects of this invention are: The modified foamed TPU material prepared by this invention is composed of thermoplastic polyurethane, EVA, polyolefin elastomer, POE-g-MAH, reinforcing agent, zinc stearate and antioxidant. This material has excellent resilience, wear resistance and mechanical properties, and its application in the inner core layer of Peak rackets has good application prospects.

[0013] The modified foamed TPU material of this invention incorporates a reinforcing agent. This reinforcing agent uses mesoporous silica as a core, onto which a polymer is grafted. This polymer is produced by a free radical reaction of styrene, a modifier, and long-chain hydrophobic alkyl acrylates. In this reinforcing agent, the mesoporous silica acts as a rigid core and physical crosslinking point, uniformly dispersed in the TPU matrix. Its high specific surface area allows for strong interaction with the polymer chains, forming a "bonded rubber" layer that restricts molecular chain slippage and creates a stable physical crosslinking network. When the material is subjected to external force, the TPU molecular chains can rapidly slide and rearrange along the surface of the mesoporous silica particles. After the external force is removed, the molecular chains recover their original shape through thermal motion, efficiently converting mechanical energy into heat energy for dissipation, thereby improving resilience. Furthermore, the surface polymer incorporates borate ester structures and polyether segments. The dynamically covalently bonded borate esters can reversibly break and recombine under external force, efficiently dissipating energy like countless tiny "shock absorbers." The flexible polyether segments provide excellent mobility for the molecular chains, forming the basis for high resilience. Reinforcing agents can also improve the mechanical properties of materials by utilizing the core-shell structure. In addition, the polymer chains on the surface of the reinforcing agent can form a lubricating layer in the matrix, effectively resisting friction and scratching, and extending the service life of the product. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of a racket according to the present invention.

[0016] The attached diagram lists the components represented by each number as follows: 1. First surface layer; 2. Inner core layer; 3. Second surface layer. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The mesoporous silica in the following examples was prepared in the following manner: 1.2 g of hydroxyethyl cellulose was added to 100 mL of deionized water and heated to 90 °C to dissolve, which was recorded as the hydroxyethyl cellulose solution. 5.7 g of sodium silicate nonahydrate was stirred evenly in 35 mL of deionized water, and then slowly added dropwise to the hydroxyethyl cellulose solution over 30 min. The mixture was stirred evenly, the pH was adjusted to 5, and the reaction was stirred for 2 h. The mixture was then stirred at room temperature for 24 h, aged for 24 h, centrifuged, washed, dried, ground, and then calcined at 550 °C for 6 h. After a second grinding, mesoporous silica was obtained.

[0019] Example 1: The reinforcing agent was prepared by the following steps: Step A1: Under nitrogen atmosphere, add 0.2 mol polyethylene glycol monomethyl ether-350 and 0.1 mol 4-vinylphenylboronic acid to 200 mL toluene, mix and stir until homogeneous, heat to 110 °C, reflux at constant temperature for 6.5 h, remove water and toluene by azeotropic reaction, and dry to obtain the modifier. Step A2: Add 2g of mesoporous silica to 80mL of ethanol and reflux for 30min. Then add 0.5mL of KH570 and 8mL of deionized water, and maintain the reflux reaction at 50℃ for 6h. Filter, wash and dry to obtain modified silica. Step A3: Disperse 1g of modified silica evenly in 100mL of anhydrous toluene using ultrasonication. Then add a mixture of 0.35mol styrene, 0.05mol modifier and 0.02mol lauryl acrylate and stir evenly. Then add 0.4g benzoyl peroxide and stir evenly. Purge with nitrogen gas and heat to 80℃ and stir for 20h. Centrifuge, filter, wash with anhydrous toluene and dry to obtain the reinforcing agent.

[0020] Example 2: The reinforcing agent was prepared by the following steps: Step A1: Under nitrogen atmosphere, add 0.2 mol polyethylene glycol monomethyl ether-350 and 0.1 mol 4-vinylphenylboronic acid to 200 mL toluene, mix and stir until homogeneous, heat to 110 °C, reflux at constant temperature for 6.5 h, remove water and toluene by azeotropic reaction, and dry to obtain the modifier. Step A2: Add 2g of mesoporous silica to 80mL of ethanol and reflux for 30min. Then add 0.5mL of KH570 and 8mL of deionized water, and maintain the reflux reaction at 50℃ for 6h. Filter, wash and dry to obtain modified silica. Step A3: Disperse 1g of modified silica evenly in 100mL of anhydrous toluene using ultrasonication. Then add a mixture of 0.35mol styrene, 0.065mol modifier and 0.03mol docosyl acrylate and stir until homogeneous. Next, add 0.5g benzoyl peroxide and stir until homogeneous. Purge with nitrogen gas and heat to 80℃ and stir for 22h. Centrifuge, filter, wash with anhydrous toluene and dry to obtain the reinforcing agent.

[0021] Example 3: The reinforcing agent was prepared by the following steps: Step A1: Under nitrogen atmosphere, add 0.2 mol polyethylene glycol monomethyl ether-350 and 0.1 mol 4-vinylphenylboronic acid to 200 mL toluene, mix and stir until homogeneous, heat to 110 °C, reflux at constant temperature for 8.5 h, remove water and toluene by azeotropic reaction, and dry to obtain the modifier. Step A2: Add 2g of mesoporous silica to 120mL of ethanol and reflux for 30min. Then add 1mL of KH570 and 15mL of deionized water, and maintain the reflux reaction at 60℃ for 6h. Filter, wash and dry to obtain modified silica. Step A3: Disperse 1g of modified silica evenly in 100mL of anhydrous toluene using ultrasonication. Then add a mixture of 0.25mol styrene, 0.08mol modifier and 0.04mol tetradecyl acrylate and stir until homogeneous. Next, add 0.6g benzoyl peroxide and stir until homogeneous. Purge with nitrogen gas and heat to 80℃ and stir for 24h. Centrifuge, filter, wash with anhydrous toluene and dry to obtain the reinforcing agent.

[0022] Example 4: Preparation method of modified foamed TPU material, comprising the following steps: Step S1: Add 40 parts of thermoplastic polyurethane, 15 parts of EVA, 10 parts of polyolefin elastomer (Engage8003), 3 parts of POE-g-MAH, 3 parts of the reinforcing agent prepared in Example 1, 0.2 parts of zinc stearate and 0.2 parts of antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2) to a mixer and stir evenly. Then, feed the mixture into a twin-screw extruder and extrude and granulate it at 170-180°C to obtain blended granules. Step S2: Add the blended particles into the autoclave, introduce carbon dioxide for foaming treatment, release the pressure of the autoclave within 2-3 seconds, and obtain the modified foamed TPU material. Furthermore, the foaming conditions in step S2 are: pressure of 80-150 bar, temperature of 125-135℃, and foaming time of 1.5 h.

[0023] A method for manufacturing a racket includes the following steps: Step 1: Heat thermoplastic polyurethane to 120-130℃ and then pre-impregnate it onto carbon fiber woven fabric to obtain the first and second surface layers. Step 2: The modified foamed TPU material is steam molded into an inner core layer board, thus obtaining the inner core layer. Step 3: Place the first surface layer, inner core layer, second surface layer, and side TPU strips in the mold in sequence, and hot press them at 150-160℃ and 0.3-0.6 MPa. After cooling, cut them to obtain the racket plate, and then install the handle to obtain the racket.

[0024] Example 5: Preparation method of modified foamed TPU material, comprising the following steps: Step S1: Add 50 parts of thermoplastic polyurethane, 20 parts of EVA, 15 parts of polyolefin elastomer (Engage7467), 4.5 parts of POE-g-MAH, 5.5 parts of the reinforcing agent prepared in Example 2, 0.35 parts of zinc stearate and 0.3 parts of antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2) to a mixer and stir evenly. Then feed the mixture into a twin-screw extruder and extrude and granulate it at 170-180°C to obtain blended granules. Step S2: Add the blended particles into the autoclave, introduce carbon dioxide for foaming treatment, release the pressure of the autoclave within 2-3 seconds, and obtain the modified foamed TPU material. Furthermore, the foaming conditions in step S2 are: pressure of 80-150 bar, temperature of 125-135℃, and foaming time of 2 hours.

[0025] A method for manufacturing a racket includes the following steps: Step 1: Heat thermoplastic polyurethane to 120-130℃ and then pre-impregnate it onto carbon fiber woven fabric to obtain the first and second surface layers. Step 2: The modified foamed TPU material is steam molded into an inner core layer board, thus obtaining the inner core layer. Step 3: Place the first surface layer, inner core layer, second surface layer, and side TPU strips in the mold in sequence, and hot press them at 150-160℃ and 0.3-0.6 MPa. After cooling, cut them to obtain the racket plate, and then install the handle to obtain the racket.

[0026] Example 6: Preparation method of modified foamed TPU material, comprising the following steps: Step S1: Add 60 parts of thermoplastic polyurethane, 25 parts of EVA, 20 parts of polyolefin elastomer (Engage8003), 6 parts of POE-g-MAH, 8 parts of the reinforcing agent prepared in Example 3, 0.5 parts of zinc stearate, and 0.5 parts of antioxidant (antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2) to a mixer and stir evenly. Then, feed the mixture into a twin-screw extruder and extrude and granulate it at 170-180°C to obtain blended granules. Step S2: Add the blended particles into the autoclave, introduce carbon dioxide for foaming treatment, release the pressure of the autoclave within 2-3 seconds, and obtain the modified foamed TPU material. Furthermore, the foaming conditions in step S2 are: pressure of 80-150 bar, temperature of 125-135℃, and foaming time of 2.5 h.

[0027] A method for manufacturing a racket includes the following steps: Step 1: Heat thermoplastic polyurethane to 120-130℃ and then pre-impregnate it onto carbon fiber woven fabric to obtain the first and second surface layers. Step 2: The modified foamed TPU material is steam molded into an inner core layer board, thus obtaining the inner core layer. Step 3: Place the first surface layer, inner core layer, second surface layer, and side TPU strips in the mold in sequence, and hot press them at 150-160℃ and 0.3-0.6 MPa. After cooling, cut them to obtain the racket plate, and then install the handle to obtain the racket.

[0028] Comparative Example 1: This comparative example is a racket. The difference between this example and Example 6 is that the modified foamed TPU material in the inner core layer uses mesoporous silica instead of the reinforcing agent prepared in Example 3. All other aspects are the same.

[0029] Comparative Example 2: This comparative example is a racket. The difference between this example and Example 6 is that the modified silicon dioxide prepared in Example 3 is used instead of the reinforcing agent prepared in Example 3 in the modified foamed TPU material of the inner core layer. All other aspects are the same.

[0030] Performance testing: The resilience of the rackets prepared in Examples 4-6 and Comparative Examples 1-2 was tested: A Peak ball was placed 1m above a Peak racket and its rebound height was measured after free fall. The experiment was repeated 10 times and the average rebound height was calculated. The rebound height ratio of the modified foamed TPU materials in Examples 5 and 6 and Comparative Examples 1-2 was calculated based on the rebound height corresponding to the modified foamed TPU material in Example 4. The modified foamed TPU materials prepared in Examples 4-6 and Comparative Examples 1-2 were subjected to performance tests: Tensile property test: The tensile strength of the modified foamed TPU material was tested according to the HG / T 5070-2016 standard, and the tensile strength ratio of the modified foamed TPU materials in Examples 5 and 6 and Comparative Examples 1-2 was calculated based on the tensile strength of the modified foamed TPU material in Example 4 and Comparative Examples 1-2. Abrasion resistance test: The abrasion resistance of the samples was tested using a Taber abrasion tester. Two grinding wheels were placed on the sample, and the grinding wheel moving speed was set to 40 r / min to conduct the abrasion test. The initial mass of the sample and the mass of the sample after 20,000 revolutions of wear were recorded. The abrasion value of the sample was calculated using the following formula: m = m1 - m2; where m is the abrasion value of the sample, g / 20,000 r; m1 is the initial mass of the sample, g; and m2 is the mass of the sample after wear. The test results are shown in Table 1: Table 1: Performance Test Results

[0031] As can be seen from Table 1, the modified foamed TPU material prepared in this invention, as the inner core material of Peak rackets, can improve the tensile strength, wear resistance, and rebound performance of the racket.

[0032] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A racket, comprising a racket blade and a handle, characterized in that, The clapper includes an inner core layer, a first surface layer, and a second surface layer; The inner core layer is made of elastomeric plastic through a foaming process; The first and second surface layers are made of the same material, carbon fiber composite thermoplastic polyurethane.

2. The racket according to claim 1, characterized in that: The racket also includes a binding strip, which is used to seal the sides of the racket.

3. The racket according to claim 1, characterized in that, The elastomeric plastic is a modified foamed TPU material, comprising the following raw materials in parts by weight: 40-60 parts thermoplastic polyurethane, 15-25 parts EVA, 10-20 parts polyolefin elastomer, 3-6 parts POE-g-MAH, 3-8 parts reinforcing agent, 0.2-0.5 parts zinc stearate, and 0.2-0.5 parts antioxidant. The reinforcing agent is prepared by grafting double bonds onto the surface of mesoporous silica as a core, and then copolymerizing styrene, a modifier, long-chain alkane acrylate, and ethylene on the silica surface using a free radical polymerization reaction; the modifier is prepared by reacting polyethylene glycol monomethyl ether-350 and 4-vinylphenylboronic acid.

4. The racket according to claim 3, characterized in that, The reinforcing agent is prepared by the following steps: Step A1: Add polyethylene glycol monomethyl ether-350 and 4-vinylphenylboronic acid to toluene, mix and stir evenly, heat to 110℃, reflux at a constant temperature for 6.5-8.5h, remove water and toluene by azeotropic reaction, and dry to obtain the modifier. Step A2: Add mesoporous silica to excess ethanol and reflux for 30 min, then add KH570 and deionized water, maintain reflux at 50-60℃ for 6 h, filter, wash and dry to obtain modified silica. Step A3: Disperse the modified silica evenly in toluene using ultrasonication, then add a mixture of styrene, modifier, and long-chain alkane acrylate and stir until homogeneous. Next, add benzoyl peroxide and stir until homogeneous. Purge with nitrogen gas and heat to 80°C and stir for 20-24 hours. Centrifuge, filter, wash with anhydrous toluene, and dry to obtain the reinforcing agent.

5. The racket according to claim 4, characterized in that, In step A1, the molar ratio of polyethylene glycol monomethyl ether-350 to 4-vinylphenylboronic acid is 2:

1.

6. The racket according to claim 4, characterized in that, In step A2, the ratio of mesoporous silica, ethanol, KH570 and deionized water is 2g:80-120mL:0.5-1mL:8-15mL.

7. The racket according to claim 4, characterized in that, In step A3, the ratio of modified silica, toluene, styrene, modifier, long-chain acrylate alkane, and benzoyl peroxide is 1g:100mL:0.2-0.4mol:0.05-0.08mol:0.02-0.04mol:0.4-0.6g, wherein the long-chain acrylate alkane is one of lauryl acrylate, tetradecyl acrylate, or docosyl acrylate.

8. The racket according to claim 4, characterized in that, The method for preparing the inner core material. Preparation includes the following steps: Step S1: Add thermoplastic polyurethane, EVA, polyolefin elastomer, POE-g-MAH, reinforcing agent, zinc stearate and antioxidant to a mixer and stir evenly. Then feed the mixture into a twin-screw extruder and extrude and granulate it at 170-180℃ to obtain blended granules. Step S2: Add the blended particles to the autoclave, introduce carbon dioxide for foaming treatment, release the pressure of the autoclave within 2-3 seconds, and obtain the modified foamed TPU material.

9. The racket according to claim 4, characterized in that, The foaming conditions described in step S2 are: pressure of 80-150 bar, temperature of 125-135℃, and foaming time of 1-3 hours.

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