Ventilated modified epdm particle composite sports plastic ground and its molding method

Abstract

This invention discloses a breathable modified EPDM granule composite sports plastic field and its molding method, comprising an elastomer base layer formed by bonding and curing an adhesive, modified EPDM granules, and microcapsules. The elastomer base layer has a gradient pore structure with decreasing pore size from bottom to top. The gradient pore structure is achieved through a layered composite structure, consisting of a surface layer, a transition layer, and a bottom layer from top to bottom. By constructing a gradient pore structure from bottom to top, the large pore size of the bottom layer ensures rapid water infiltration and drainage, while the dense structure of the surface layer meets the requirements for flatness and sports performance. At the same time, relying on the strong interfacial bonding formed by the "amino-epoxy" chemical synergistic network, the material maintains high porosity while possessing excellent tensile strength and good elasticity.

Description

Technical Field

[0001] This invention relates to the field of plastic sports field technology, and more particularly to a breathable modified EPDM granule composite sports sports field and its molding method. Background Technology

[0002] Sports plastic surfaces are widely used in various sports fields such as athletic fields, basketball courts, and tennis courts due to their good elasticity, slip resistance, and wear resistance. Among them, EPDM (ethylene propylene diene monomer rubber) granule composite plastic surfaces have become one of the mainstream products due to their excellent weather resistance, aging resistance, and elastic recovery ability.

[0003] Existing EPDM granule composite plastic sports fields mostly adopt a single-pore structure design, which presents a problem of difficulty in balancing air permeability and structural stability: if the pores are too large, the field has good air permeability but insufficient load-bearing capacity and is prone to deformation; if the pores are too small, the structural stability is improved but the air permeability and drainage effect is poor, and water is easy to accumulate after rain, affecting sports safety and the service life of the field. At the same time, the existing EPDM granules have low surface polarity, and the bonding strength with the adhesive is limited. After long-term use, granules are prone to problems such as granule shedding and delamination, reducing the durability of the field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides the following technical solution: On the one hand, a breathable modified EPDM granule composite sports plastic field is provided. It includes an elastomer base layer formed by bonding and curing adhesives, modified EPDM particles and microcapsules. The elastomer base layer has a gradient pore structure with decreasing pore size from bottom to top. The gradient pore structure is achieved through a layered composite structure, consisting of a surface layer, a transition layer and a bottom layer from top to bottom.

[0005] As an improvement to the above technical solution, the preparation method of the modified EPDM particles is as follows: S1: Immerse EPDM particles in a hydrolysate prepared from aminosilane coupling agent, alcohol solvent and deionized water, and stir for 10-60 min; then filter out the particles and heat treat them at 100-130℃ for 0.5-2 h to obtain ammoniated EPDM particles. S2: The functionalized particles are immersed in a hydrolysate prepared from long-chain alkylsilane, alcohol solvent and deionized water, and stirred for 10-40 min; then the particles are filtered out and heat-treated at 80-120℃ for 0.5-2 h to obtain modified EPDM particles.

[0006] As an improvement to the above technical solution, the method for preparing the microcapsules includes the following steps: S1. Preparation of wall material prepolymer solution: Prepare a mixed aqueous solution containing urea-formaldehyde resin prepolymer and aqueous epoxy resin emulsion; S2. Preparation of core material emulsion: The amine curing agent used as the core material is emulsified and dispersed in an aqueous phase containing an emulsifier to form an oil-in-water emulsion; S3. In-situ polymerization coating: The wall material prepolymer solution is added to the core material emulsion, and a condensation reaction is carried out under acidic conditions, so that the urea-formaldehyde resin prepolymer and the epoxy resin component are co-deposited and cross-linked on the surface of the core material droplets to form a composite capsule wall with reactive epoxy groups, thereby coating the amine curing agent core material to obtain the microcapsules.

[0007] As an improvement to the above technical solution, the amine compound is selected from one or more of ethylenediamine, diethylenetriamine, and triethylenetetramine.

[0008] As an improvement to the above technical solution, the adhesive comprises bisphenol A type epoxy resin and polypropylene glycol diglycidyl ether, wherein the mass ratio of bisphenol A type epoxy resin to polypropylene glycol diglycidyl ether is 100:(5-25).

[0009] As an improvement to the above technical solution, the bottom layer uses large-particle-size modified EPDM particles with a particle size range of 4-6 mm, and the ratio of modified EPDM particles: binder: microcapsules is 100: (5-8): (0.5-2). The transition layer uses medium-sized modified EPDM particles with a particle size range of 2-4 mm, and the ratio of modified EPDM particles: binder: microcapsules is 100: (8-12): (0.5-1.5). The surface layer uses small-particle-size modified EPDM particles with a particle size range of 0.8-1.2 mm, and the ratio of modified EPDM particles: binder: microcapsules is 100: (12-18): (1-3).

[0010] On the other hand, a method for molding breathable modified EPDM granules into composite sports plastic surfaces is provided, including the following steps: S1: Modified EPDM particles of different particle sizes are mixed with microcapsules respectively. Through friction, the electrostatic adsorption force is used to make the microcapsules preferentially adhere to the depressions or friction parts on the particle surface. S2: After mixing the large-diameter composite particles with the adhesive evenly, mechanically spread the mixture to a thickness of 7-10mm. After light vibration compaction, cure at room temperature for 8-12 hours to form the base layer. S3: After the base layer has fully cured, spread the mixture of composite particles and adhesive, control the spreading thickness to 3-5mm, level it, and cure it at room temperature for 6-8 hours to form a transition layer; S4: After the transition layer has cured, spread a mixture of small-particle composite particles and adhesive, control the spreading thickness to 2-3mm, and simultaneously press the anti-slip texture and cure at room temperature for 12-16 hours to form the surface layer.

[0011] The beneficial effects of this invention are: By constructing a bottom-up gradient pore structure, the large pore size at the bottom layer ensures rapid water infiltration and discharge, while the dense structure at the surface layer meets the requirements for flatness and motion performance. At the same time, relying on the strong interfacial bonding formed by the "amino-epoxy" chemical synergistic network, the material maintains high porosity while possessing excellent tensile strength and good elasticity. The modified EPDM particles, microcapsules and adhesives form a three-dimensional network with covalent bonds, transforming the particles from physical fillers into chemical cross-linking points in the network. This effectively resists moisture erosion, freeze-thaw cycles and long-term dynamic loads, significantly reducing defects such as particle shedding and surface powdering, and greatly extending the service life of the site. To prevent pores from collapsing and becoming blocked under long-term loads, this invention utilizes the combined effect of microcapsules breaking at particle contact points to form chemical welds and low surface energy hydrophobic regions on the particle surface. This ensures that the pore morphology after curing is firmly "locked" by the chemical network, maintaining the stability of its gradient pore structure even under repeated impacts and pressures. This avoids the attenuation of permeability due to pore collapse and guarantees the long-term effectiveness of drainage performance. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0013] Reference numerals: 1. Bottom layer; 2. Transition layer; 3. Top layer. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0015] During the compaction process, the microcapsules rupture, releasing the amine curing agent within the microcapsule core. This agent rapidly undergoes an addition polymerization reaction with the epoxy groups in the epoxy resin adhesive, forming a continuous, three-dimensionally cross-linked epoxy resin matrix. This matrix constitutes the main mechanical framework of the entire material. The ruptured microcapsule wall fragments (containing epoxy groups) are dispersed in the system. The epoxy groups on the wall fragments react with the amino groups on the surface of the modified particles, forming strong covalent bonds between the particles and fragments. Simultaneously, these wall fragments themselves also participate in the main epoxy network through their epoxy groups. The epoxy groups in the adhesive can also directly react with the amino groups on the particle surface. Through these reactions, an integrated interpenetrating network is formed, tightly bonded by covalent bonds between the particles (amino groups), microcapsule wall fragments (epoxy groups), and adhesive matrix (epoxy network). The particles are no longer isolated fillers but become chemical cross-linking points in the entire supporting network. Meanwhile, the "low surface energy hydrophobic zone" on the surface of the modified EPDM particles effectively repels the adhesive from spreading over a large area on its surface, forcing the adhesive to be confined to the limited contact area between particles. This "spot welding" type of bonding ensures the overall structural strength while completely preserving the macroscopic interconnected pore channels formed by particle accumulation, thus achieving a highly efficient balance between structural strength and porosity.

[0016] Preparation of modified EPDM particles: Weigh 100 kg of EPDM particles, mix 3 kg of N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH-792) with 30 kg of ethanol and 67 kg of deionized water, adjust the pH to 5 with acetic acid, and hydrolyze for 1 hour to obtain an aminosilane hydrolysate. Immerse the EPDM particles in the hydrolysate, stir for 30 minutes, filter, and heat-treat in an oven at 120°C for 1 hour to obtain aminated EPDM particles. Immerse the above aminated particles in a hydrophobic silane hydrolysate prepared with 2 kg of octyltrimethoxysilane, 30 kg of ethanol, and 68 kg of deionized water, stir for 20 minutes, filter, and heat-treat in an oven at 100°C for 1 hour to obtain modified EPDM particles. Microcapsule preparation: Add 15 kg of urea and 40 kg of 37% formaldehyde solution to a three-necked flask, and use 10%... Adjust the pH to 8.5 with NaOH solution, stir at 70℃ for 1.5 hours to obtain a transparent urea-formaldehyde resin prepolymer solution. Cool to room temperature, add 10g of aqueous bisphenol A type epoxy resin emulsion (50% solid content), stir evenly to obtain a wall material prepolymer mixture. In another container, add 2kg of gum arabic, 1kg of sodium dodecylbenzenesulfonate, and 100kg of deionized water, stir to dissolve, add 30kg of diethylenetriamine, emulsify at 10000rpm for 15 minutes to form a stable emulsion, slowly add the wall material prepolymer mixture dropwise to the emulsion, stir mechanically, adjust the pH of the system to 3.5 with 10% citric acid solution, heat to 50℃, and react for 3 hours. After the reaction is complete, adjust the pH to 7.0 with NaOH solution, filter, wash with deionized water and ethanol, and vacuum dry at 40℃ for 12 hours to obtain microcapsules with a particle size distribution of 20-80μm. Example 1 The mass ratio of bisphenol A epoxy resin to polypropylene glycol diglycidyl ether in the adhesive is 100:5; Bottom layer 1 (modified EPDM particles with a particle size of 4-6mm), the ratio of modified EPDM particles: binder: microcapsules is 100:5:2; Transition layer 2 (modified EPDM particles with a particle size of 2-4 mm), the ratio of modified EPDM particles: binder: microcapsules is 100:8:1.5; Surface layer 3 (modified EPDM particles with a particle size of 0.8-1.2mm), the ratio of modified EPDM particles: binder: microcapsules is 100:12:3; Modified EPDM particles of different particle sizes are mixed with microcapsules according to the specified ratio. Through friction, the microcapsules are preferentially attached to the depressions or friction areas on the particle surface by electrostatic adsorption force to form composite particles. After the large-diameter composite particles are mixed evenly with the adhesive, they are mechanically spread to a thickness of 7mm. After being compacted by light vibration, they are cured at room temperature for 8 hours to form the base layer. After the base layer has fully cured, the mixture of composite particles and adhesive is spread, with the spreading thickness controlled at 3mm. After leveling, it is cured at room temperature for 6 hours to form a transition layer. After the transition layer has cured, spread a mixture of small-diameter composite particles and adhesive, control the spreading thickness to 2mm, and simultaneously press the anti-slip texture and cure at room temperature for 12 hours to form the surface layer. Example 2

[0017] The mass ratio of bisphenol A epoxy resin to polypropylene glycol diglycidyl ether in the adhesive is 100:10; Layer ratio: Bottom layer 1 (modified EPDM particles with a particle size of 4-6mm), modified EPDM particles: binder: microcapsules ratio is 100:6:1; Transition layer 2 (modified EPDM particles with a particle size of 2-4 mm), the ratio of modified EPDM particles: binder: microcapsules is 100:9:1; Surface layer 3 (modified EPDM particles with a particle size of 0.8-1.2mm), the ratio of modified EPDM particles: binder: microcapsules is 100:14:2; Modified EPDM particles of different particle sizes are mixed with microcapsules according to the specified ratio. Through friction, the microcapsules are preferentially attached to the depressions or friction areas on the particle surface by electrostatic adsorption force to form composite particles. After the large-diameter composite particles are mixed evenly with the adhesive, they are mechanically spread to a thickness of 8mm. After being compacted by light vibration, they are cured at room temperature for 9 hours to form the bottom layer 1. After the bottom layer 1 has fully cured, the mixture of composite particles and adhesive is spread, the thickness is controlled at 4mm, and after leveling, it is cured at room temperature for 7 hours to form the transition layer 3. After the transition layer 2 has cured, spread a mixture of small-particle composite particles and adhesive, control the spreading thickness to 2.5mm, and simultaneously press the anti-slip texture and cure at room temperature for 14 hours to form the surface layer 3. Example 3

[0018] The mass ratio of bisphenol A epoxy resin to polypropylene glycol diglycidyl ether in the adhesive is 100:20. The ratio of each layer is as follows: Bottom layer 1 (modified EPDM particles with a particle size of 4-6mm), the ratio of modified EPDM particles: binder: microcapsules is 100:7:1.5; Transition layer 2 (modified EPDM particles with a particle size of 2-4 mm), the ratio of modified EPDM particles: binder: microcapsules is 100:11:1.2; Surface layer 3 (modified EPDM particles with a particle size of 0.8-1.2mm), the ratio of modified EPDM particles: binder: microcapsules is 100:16:2.5; Modified EPDM particles of different particle sizes are mixed with microcapsules according to the specified ratio. Through friction, the microcapsules are preferentially attached to the depressions or friction areas on the particle surface by electrostatic adsorption force to form composite particles. After the large-diameter composite particles are mixed evenly with the adhesive, they are mechanically spread to a thickness of 9mm. After being compacted by light vibration, they are cured at room temperature for 11 hours to form the bottom layer 1. After the bottom layer 1 has completely cured, the mixture of composite particles and adhesive is spread, the paving thickness is controlled at 4mm, and after leveling, it is cured at room temperature for 7 hours to form the transition layer 2. After the transition layer 2 has cured, spread a mixture of small-particle composite particles and adhesive, control the spreading thickness to 3mm, and simultaneously press the anti-slip texture and cure at room temperature for 16 hours to form the surface layer 3. Example 4

[0019] The mass ratio of bisphenol A epoxy resin to polypropylene glycol diglycidyl ether in the adhesive is 100:25. The ratio of each layer is as follows: Bottom layer 1 (modified EPDM particles with a particle size of 4-6mm), the ratio of modified EPDM particles: binder: microcapsules is 100:8:0.5; Transition layer 2 (modified EPDM particles with a particle size of 2-4 mm), the ratio of modified EPDM particles: binder: microcapsules is 100:12:0.5; Surface layer 3 (modified EPDM particles with a particle size of 0.8-1.2mm), the ratio of modified EPDM particles: binder: microcapsules is 100:18:1; Modified EPDM particles of different particle sizes are mixed with microcapsules according to the specified ratio. Through friction, the microcapsules are preferentially attached to the depressions or friction areas on the particle surface by electrostatic adsorption force to form composite particles. After the large-diameter composite particles are mixed evenly with the adhesive, they are mechanically spread to a thickness of 10mm. After light vibration compaction, they are cured at room temperature for 12 hours to form the bottom layer 1. After the bottom layer 1 has completely cured, the mixture of composite particles and adhesive is spread, the thickness is controlled at 5mm, and after leveling, it is cured at room temperature for 8 hours to form the transition layer 2. After the transition layer 2 has cured, spread a mixture of small-particle composite particles and adhesive, control the spreading thickness to 3mm, and simultaneously press the anti-slip texture and cure at room temperature for 16 hours to form the surface layer 3. Comparative Example 1 The only difference between this embodiment and Embodiment 2 is that in this embodiment, the EPDM particle size is 2-4mm and the overall paving thickness is 15mm. Comparative Example 2 The only difference between this embodiment and Embodiment 2 is that in this embodiment, no modification treatment of the EPDM particles is performed, and the original EPDM particles are used directly. Comparative Example 3 differs from Example 2 only in that, in this example, the adhesive is a polyurethane adhesive; Performance testing: Tensile strength and elongation at break: According to GB / T528-2009, five dumbbell-shaped specimens (thickness 2.0±0.2mm) were cut from the finished track and tested using a universal testing machine at a tensile speed of 500mm / min. Hardness was determined according to GB / T5311999; The performance of the plastic running tracks prepared in Example 14 and Comparative Example 13 was tested, and the results are shown in Table 1. Table 1 As shown in Table 1, firstly, the gradient multi-level pore structure ensures efficient drainage. The permeability coefficients of Examples 1-4 are much better than those of Comparative Example 1, proving that the layered design is effective. The large particles at the bottom layer form the main drainage channels, while the small particles at the top layer maintain pore connectivity while ensuring flatness, thus avoiding dense blockage by single-size particles. Secondly, the "spot welding" curing mechanism achieves the coexistence of strength and porosity. During construction, the microcapsules located at the particle contact points are ruptured under pressure, forming local "chemical welds". At the same time, the "low surface energy hydrophobic zone" on the particle surface forces the adhesive to be confined to the contact area. This "spot welding" bonding not only gives the overall strength but also completely preserves the macroscopic pore channels formed by particle accumulation. Finally, the "amino-epoxy" chemical synergistic network is the core of interface reinforcement. The excellent mechanical properties of the examples and comparative examples 2 and 3 show that the amino groups on the particle surface are key active sites. They covalently bond with the epoxy groups in the microcapsule wall material and adhesive, constructing chemical bridges at the interface and transforming the particles into chemical crosslinking points in the network, thereby fundamentally improving the interfacial bonding strength and matrix integrity.

[0020] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A breathable modified EPDM granule composite sports plastic field, characterized in that, It includes an elastomer base layer formed by bonding and curing adhesives, modified EPDM particles and microcapsules. The elastomer base layer has a gradient pore structure with decreasing pore size from bottom to top. The gradient pore structure is achieved through a layered composite structure, consisting of a surface layer, a transition layer and a bottom layer from top to bottom.

2. The breathable modified EPDM granule composite sports plastic field according to claim 1, characterized in that: The method for preparing the modified EPDM particles is as follows: S1: Immerse EPDM particles in a hydrolysate prepared from aminosilane coupling agent, alcohol solvent and deionized water, and stir for 10-60 min; then filter out the particles and heat treat them at 100-130℃ for 0.5-2 h to obtain ammoniated EPDM particles. S2: The functionalized particles are immersed in a hydrolysate prepared from long-chain alkylsilane, alcohol solvent and deionized water, and stirred for 10-40 min; then the particles are filtered out and heat-treated at 80-120℃ for 0.5-2 h to obtain modified EPDM particles.

3. The breathable modified EPDM granule composite sports plastic field according to claim 2, characterized in that: The method for preparing the microcapsules includes the following steps: S1. Preparation of wall material prepolymer solution: Prepare a mixed aqueous solution containing urea-formaldehyde resin prepolymer and aqueous epoxy resin emulsion; S2. Preparation of core material emulsion: The amine curing agent used as the core material is emulsified and dispersed in an aqueous phase containing an emulsifier to form an oil-in-water emulsion; S3. In-situ polymerization coating: The wall material prepolymer solution is added to the core material emulsion, and a condensation reaction is carried out under acidic conditions, so that the urea-formaldehyde resin prepolymer and the epoxy resin component are co-deposited and cross-linked on the surface of the core material droplets to form a composite capsule wall with reactive epoxy groups, thereby coating the amine curing agent core material to obtain the microcapsules.

4. The breathable modified EPDM granule composite sports plastic field and its molding method according to claim 3, characterized in that: The amine compound is selected from one or more of ethylenediamine, diethylenetriamine, and triethylenetetramine.

5. The breathable modified EPDM granule composite sports plastic field according to claim 1, characterized in that: The adhesive comprises bisphenol A type epoxy resin and polypropylene glycol diglycidyl ether, wherein the mass ratio of bisphenol A type epoxy resin to polypropylene glycol diglycidyl ether is 100:(5-25).

6. The breathable modified EPDM granule composite sports plastic field according to claim 1, characterized in that: The bottom layer uses large-particle-size modified EPDM particles with a particle size range of 4-6 mm, and the ratio of modified EPDM particles: binder: microcapsules is 100: (5-8): (0.5-2). The transition layer uses medium-sized modified EPDM particles with a particle size range of 2-4 mm, and the ratio of modified EPDM particles: binder: microcapsules is 100: (8-12): (0.5-1.5). The surface layer uses small-particle-size modified EPDM particles with a particle size range of 0.8-1.2 mm, and the ratio of modified EPDM particles: binder: microcapsules is 100: (12-18): (1-3).

7. A molding method for a breathable modified EPDM granule composite sports plastic field as described in claim 1, comprising the following steps: S1: Modified EPDM particles of different particle sizes are mixed with microcapsules respectively. Through friction, the electrostatic adsorption force is used to make the microcapsules preferentially adhere to the depressions or friction parts on the particle surface. S2: After mixing the large-diameter composite particles with the adhesive evenly, mechanically spread the mixture to a thickness of 7-10mm. After light vibration compaction, cure at room temperature for 8-12 hours to form the base layer. S3: After the base layer has fully cured, spread the mixture of composite particles and adhesive, control the spreading thickness to 3-5mm, level it, and cure it at room temperature for 6-8 hours to form a transition layer; S4: After the transition layer has cured, spread a mixture of small-particle composite particles and adhesive, control the spreading thickness to 2-3mm, and simultaneously press the anti-slip texture and cure at room temperature for 12-16 hours to form the surface layer.

Images