PU (polyurethane) conveying belt with highly wear-resistant surface layer

Abstract

The invention discloses a PU conveying belt with a highly wear-resistant surface layer, and belongs to the field of conveying belts. The PU conveying belt comprises a framework fabric and a high-wear-resistance surface layer, the high-wear-resistance surface layer is prepared from the following raw materials in parts by mass: 100 parts of TPU, 4 to 8 parts of short carbon fiber, 0.5 to 1 part of graphene / silicon dioxide composite particles and 1 to 3 parts of antioxidant. The graphene / silicon dioxide composite particles take graphene as a core layer and silicon dioxide as a shell layer; the surfaces of the graphene / silicon dioxide composite particles are grafted with branched polymethyl methacrylate. Graphene / silicon dioxide composite particles can block extension of cracks in the abrasion process, the load transmission efficiency of a system interface is improved, the abrasion resistance of the abrasion-resistant surface layer is improved, branched polymethyl methacrylate is grafted to the surface, the dispersity and compatibility of the composite particles can be improved, and the abrasion resistance of the abrasion-resistant surface layer is improved. And moreover, the problem that the flexibility is reduced due to the addition of rigid particles can be solved, and high wear resistance and high extension are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of conveying belt, in particular to a PU conveying belt with high wear-resistant surface layer. BACKGROUND

[0002] The conveying belt is an important part of the belt conveyor, which mainly plays a role of traction and load bearing in the conveyor, and can be applied to coal, metallurgy, chemical industry, food and transportation and other fields, and can be used for large-scale continuous transportation, and is widely used in industrial and mining enterprises. The materials transported by the conveyor can be blocky, powdery, pasty or piece goods, and can also be various slurries.

[0003] At present, in order to realize the continuous and efficient production of transportation, the rapid development of the conveying belt has great significance on technology and economic benefits. The conveying belt is mainly composed of a skeleton material and a covering rubber layer. The skeleton material is the core part of the conveying belt and bears all the loads during work. The raw materials of the covering rubber layer are various, and the polyurethane (PU) has high elasticity of rubber and rigidity of plastic. Its superior mechanical properties and environmental protection concept have attracted widespread attention.

[0004] However, in the actual production process, some sharp solid materials with different shapes and edges will cause direct impact and friction on the conveying belt during the operation of the PU conveying belt. Long-term material wear and impact will gradually thin the polyurethane covering layer, and even leave scratches or cracks on the rubber layer, thereby being eroded by the outside world. In heavy load work, the degree of wear will gradually increase, and serious wear will cause the fracture of the conveying belt, thereby causing wear and erosion of the skeleton material, and greatly reducing the service life of the conveying belt.

[0005] Therefore, improving the wear resistance and strength of the conveying belt can greatly prolong the service life of the conveying belt without changing other structures. At present, people have made a lot of researches on improving the wear resistance of the conveying belt, and have tried to improve the wear resistance of the covering rubber material by formula design, addition of wear-resistant main machine, and blending with wear-resistant materials. However, these modification methods usually sacrifice the flexibility and temperature resistance of the covering rubber layer, which greatly reduces the application range of the conveying belt. Therefore, it is of great significance to obtain a PU conveying belt with high wear resistance and high performance. SUMMARY

[0006] The present application provides a PU conveying belt with high wear-resistant surface layer, which can solve the problem of poor wear resistance of the conveying belt in the prior art.

[0007] The present application provides a PU conveying belt with high wear-resistant surface layer, which comprises a skeleton fabric and a high wear-resistant surface layer; the high wear-resistant surface layer comprises the following raw materials in parts by mass: TPU 100 parts; Short carbon fibers 4-8 parts; Graphene / silica composite particles 0.5-1 part; Antioxidants 1-3 parts; The graphene / silica composite particles have graphene as a core layer and silica as a shell layer.

[0008] Preferably, the length of the short carbon fibers is 2-8 mm, and the fiber diameter is 5-11 mu m.

[0009] Preferably, the antioxidants include a combination of one or more of antioxidant 1010, antioxidant 168, antioxidant 1076, and antioxidant BHT.

[0010] Preferably, the raw material of the framework fabric includes a mixed fabric of one or more of cotton fibers, polyamide fibers, and polyester fibers.

[0011] By using the above technical solution, short carbon fibers are added to the TPU matrix material, which can form a three-dimensional network framework in the matrix to directly share the external load and inhibit the crack propagation of the matrix temporal part, while improving the mechanical properties of the material.

[0012] The graphene / silica composite particles are also added to the TPU matrix material, wherein the graphene core layer mainly utilizes its unique two-dimensional sheet structure to block the extension of cracks during the wear process and enhance the load transfer efficiency of the system interface.

[0013] Therefore, the graphene / silica composite particles are selected, and a layer of silica is further compounded outside the graphene.

[0014] The silica shell layer can improve the dispersibility of the particles and enhance the performance of the surface layer material, but the compatibility between the silica and the hydrophobic TPU matrix material is not good due to the presence of many polar groups on the surface of the silica, which affects the mechanical properties of the surface layer material and the improvement of the wear resistance of the surface layer.

[0015] As a high-molecular interfacial layer, the ester group in the polymethyl methacrylate can form hydrogen bonds with the groups in the TPU matrix material, thereby improving the compatibility of the graphene / silica composite particles in the matrix material, allowing the composite particles to be uniformly dispersed in the matrix material as a rigid support structure, and through the interaction between the branched polymethyl methacrylate and the matrix material, the interfacial bonding force between the composite particles and the matrix material can be enhanced, effectively avoiding the shedding or migration of the composite particles due to friction during application, resulting in a gradual decrease in the wear resistance of the surface layer.

[0016] Moreover, the branched structure has more free segments than linear polymethyl methacrylate. Compared with directly adding wear-resistant rigid particles, the flexible long chains of branched polymethyl methacrylate can not only absorb impact energy and help reduce interfacial stress concentration and crack growth, but also greatly improve the problem of decreased flexibility caused by the addition of rigid particles. The branched polymethyl methacrylate can impart higher segment mobility to the surface layer material, helping the surface layer material to improve wear resistance while still maintaining good flexibility, balancing the wear resistance and flexibility of the material, obtaining a high-performance conveyor belt surface layer material, and improving the service life of the material.

[0017] Preferably, the raw materials of the graphene / silica composite particles include graphene / silica core-shell particles, methyl methacrylate, and branched monomers in a mass ratio of 1:(0.7-0.9):(0.03-0.05).

[0018] Preferably, the raw materials of the graphene / silica core-shell particles include tetraethyl orthosilicate and graphene oxide in a mass ratio of 1:(0.015-0.02).

[0019] Preferably, the graphene / silica core-shell particles are prepared by the following method: The graphene oxide is dispersed in a solvent, the pH value of the solution is adjusted to 11-12, the temperature is raised to 60-70°C, a non-ionic surfactant and urea are added, stirring is performed for 4-6 h, tetraethyl orthosilicate and amino silane coupling agent are added, stirring is performed for 20-30 h, and finally filtration, washing, and drying are performed.

[0020] More preferably, the solvent includes any one of diethylene glycol butyl ether, N-methyl pyrrolidone, N,N-dimethylacetamide, and anisole.

[0021] More preferably, the non-ionic surfactant includes a combination of one or more of octylphenol polyoxyethylene ether and alkyl glycoside; the mass ratio of the non-ionic surfactant to tetraethyl orthosilicate is (1-1.3):1.

[0022] More preferably, the mass ratio of urea to tetraethyl orthosilicate is (0.5-0.7):1.

[0023] More preferably, the amino silane coupling agent includes a combination of one or more of gamma-aminopropyl triethoxysilane, gamma-aminopropyl trimethoxysilane, gamma-aminopropyl methyldiethoxysilane and N-aminoethyl-gamma-aminopropyl trimethoxysilane; the mass ratio of the amino silane coupling agent and tetraethyl orthosilicate is (0.2-0.3):1.

[0024] Preferably, the branched monomer includes a combination of one or more of ethylene glycol dimethacrylate, p-divinylbenzene, p-vinyl benzyl methacrylate and 2-(diisopropylamino)ethyl methacrylate.

[0025] Preferably, the graphene / silica composite particles are prepared by the following method: The graphene / silica core-shell particles are dispersed in an aqueous urea solution, stirred and dispersed at 60-65°C for 2-3h, then methyl methacrylate, an initiator, a branched monomer and an auxiliary agent are added, stirred and reacted at 90-95°C under a nitrogen atmosphere for 2-3h, and finally precipitated, washed and dried.

[0026] More preferably, the mass ratio of the urea and the graphene / silica core-shell particles is (0.1-0.2):1.

[0027] More preferably, the initiator includes any one of 2-bromoisobutyryl bromide, pentamethyldiethylenetriamine and ammonium persulfate; the mass ratio of the initiator and the graphene / silica core-shell particles is (0.03-0.04):1.

[0028] More preferably, the auxiliary agent is a mixture of copper bromide and 2,2'-bipyridine in a molar ratio of 1:3; the mass ratio of the auxiliary agent and the graphene / silica core-shell particles is (0.06-0.07):1.

[0029] By adopting the technical scheme, the graphene / silica composite particles of the present application, wherein the graphene / silica core-shell particles contained therein take graphene as a main mechanical bearing layer, take silica as a wear-resistant reinforcing shell layer, and improve the wear resistance and tensile strength of the surface layer material as a rigid core, can not only optimize the structural performance of graphene, but also improve the wear resistance of the composite particles.

[0030] On this basis, the graphene / silica core-shell particles are modified and grafted with polymethyl methacrylate on the surface, on the one hand, the flexible chain segments of the branched polymethyl methacrylate can absorb impact energy and inhibit the generation of material cracks, thereby improving the wear resistance of the material. On the other hand, the branched polymethyl methacrylate forms a flexible barrier on the surface of the graphene / silica core-shell particles, which can reduce the occurrence of agglomeration, improve the dispersibility and compatibility of the composite particles in the matrix material, the ester groups can form a hydrogen bond network between the ester groups of the matrix material, and the branched segments can also anchor the TPU molecular chains through physical entanglement to form a certain ion-polymer interpenetrating network structure, thereby improving the interfacial bonding force of the composite particles in the matrix material, reducing the problems such as the shedding of the composite particles caused by friction during application, and improving the long-term wear resistance of the material.

[0031] Moreover, the branched polymethyl methacrylate can also be compatible with the soft segment of the TPU matrix material, ensuring the low-temperature flexibility of the surface layer material, balancing the wear resistance and impact resistance of the surface layer material, and making up for the problem of decreased flexibility caused by the addition of rigid particles. Through the speed-up effect and interface buffering effect of the branched polymethyl methacrylate, high wear resistance and high elongation of the surface layer material can coexist.

[0032] Preferably, the TPU is a polyether type TPU.

[0033] By adopting the above technical solution, the molecular chain flexibility of the polyether type TPU is higher than that of the polyester type TPU, which can maintain good elasticity at low temperature and reduce the possibility of catalytic cracking, thereby widening the application range of the obtained PU conveyor belt. Moreover, the polarity of the polyether type TPU is lower, which is more conducive to enhancing the dispersibility of the substance in the matrix material and improving the compatibility between the branched polymethyl methacrylate, and the two can better offset the problem of decreased flexibility caused by the rigid filler, thereby improving the wear resistance while maintaining good anti-deformation ability.

[0034] Preferably, the raw material of the high wear-resistant surface layer further includes 3-6 parts by mass of polyborosiloxane.

[0035] By adopting the above technical solution, in the preparation process of the high wear-resistant surface layer material, the graphene / silica composite particles may be subjected to thermal degradation of the soft segment molecular chains of the matrix material under high temperature, resulting in a decrease in interfacial bonding force, which makes the composite particles have a tendency to aggregate outward, leading to uneven distribution of the composite particles and easy shedding of the composite particles due to scratching during application, and losing wear resistance.

[0036] In order to improve this problem, polyborosiloxane is added in the preparation process of the high wear-resistant surface layer material, which can form a thermal barrier around the graphene / silica composite particles to improve the heat resistance of the interface, and can also form a covalent bond with the branched polymethyl methacrylate to anchor the position of the composite particles in the matrix material, thereby reducing the migration of the composite particles.

[0037] And the boron atoms in the polysiloxane can form coordination bonds with the TPU matrix and cooperate to branched polymethyl methacrylate segments, thereby enhancing the interface stress transfer, improving the mechanical strength of the surface layer material, and improving the long-term stability of the material.

[0038] Preferably, the PU conveyor belt with high wear-resistant surface layer is prepared according to the following process steps: S1. The raw materials of the high wear-resistant surface layer are weighed according to the corresponding mass fraction, mixed uniformly, and then extruded and granulated to obtain the high wear-resistant surface layer master batch; S2. Qualitative heat treatment is performed on the skeleton fabric, and the temperature is controlled at 160-190 DEG C; S3. The polyurethane glue is coated on one side surface of the skeleton fabric, and dried at 120-140 DEG C; S4. The high wear-resistant surface layer master batch is extruded and calendered on the side of the skeleton fabric coated with the polyurethane glue, to form the high wear-resistant surface layer, wherein the calendering temperature is 170-200 DEG C, and the pressure is 10-15 Pa; S5. After calendering and compounding, cooling to room temperature, the PU conveyor belt with high wear-resistant surface layer is obtained.

[0039] Preferably, in the step S1, the raw materials of the high wear-resistant surface layer can also include polysiloxane.

[0040] The beneficial effects of the present application are: 1. In the PU conveyor belt with high wear-resistant surface layer of the present application, the raw materials of the high wear-resistant surface layer include graphene / silica composite particles, graphene as a rigid core layer, as the main mechanical bearing layer of the composite particles, can block the extension of cracks in the wear process, enhance the load transfer efficiency of the system interface, and silica as a reinforcing shell layer, can optimize the structural performance of graphene, improve the hardness of the composite particles, and improve the wear resistance of the high wear-resistant surface layer.

[0041] 2. The graphene / silica composite particles of the present application are also grafted with branched polymethyl methacrylate, which can improve the dispersibility and compatibility of the composite particles in the matrix material as a flexible barrier, and avoid the shedding and migration of the composite particles; on the other hand, the branched polymethyl methacrylate has more flexible long chains, which can absorb impact energy, improve the low-temperature flexibility of the surface layer material, and make up for the problem of decreased flexibility caused by the addition of rigid particles, realizing the coexistence of high wear resistance and high elongation. DETAILED DESCRIPTION

[0042] The specific embodiments of the present application are described in detail below, but it should be understood that the protection scope of the present application is not limited by the specific embodiments.

[0043] Preparation Example Preparation Example 1, a graphene / silica composite particle, was prepared according to the following method: Preparation of graphene / silica core-shell particles: 200 mg of single-layer graphene oxide (flakes of 0.5-5 μm in diameter and 0.8-1.2 nm in thickness) was dispersed in 500 mL of diethylene glycol butyl ether, the pH of the solution was adjusted to 11.5, the temperature was raised to 65°C, 12 g of alkyl glycoside and 6 g of urea were added, and the mixture was stirred for 5 h. Then, 10 g of tetraethyl orthosilicate and 3 g of γ-aminopropyl triethoxysilane were added, and the mixture was stirred for 24 h. Finally, the product was obtained by filtration, washing, and drying.

[0044] Preparation of graphene / silica composite particles: 10 g of the graphene / silica core-shell particles obtained in Preparation Example 1 were dispersed in a 10% urea aqueous solution (1 g of urea was added), and the mixture was stirred at 60°C for 2 h. Then, 8 g of methyl methacrylate, 0.4 g of 2-bromoisobutyryl bromide, 0.4 g of ethylene glycol dimethacrylate, and 0.6 g of a catalyst (a mixture of copper bromide and 2,2'-bipyridine at a molar ratio of 1:3) were added, and the mixture was stirred at 90°C for 3 h under a nitrogen atmosphere. Finally, the product was obtained by precipitation, washing, and drying.

[0045] Preparation Example 2, a graphene / silica composite particle, was prepared according to the following method, except that the graphene / silica core-shell particles were prepared according to the following method: 150 mg of single-layer graphene oxide (flakes of 0.5-5 μm in diameter and 0.8-1.2 nm in thickness) was dispersed in 500 mL of diethylene glycol butyl ether, the pH of the solution was adjusted to 11.5, the temperature was raised to 65°C, 10 g of alkyl glycoside and 5 g of urea were added, and the mixture was stirred for 5 h. Then, 10 g of tetraethyl orthosilicate and 2 g of γ-aminopropyl triethoxysilane were added, and the mixture was stirred for 24 h. Finally, the product was obtained by filtration, washing, and drying.

[0046] Preparation Example 3, a graphene / silica composite particle, was prepared according to the following method, except that the graphene / silica composite particles were prepared according to the following method: 10 g of the graphene / silica core-shell particles obtained in Preparation Example 1 were dispersed in a 10% urea aqueous solution (1 g of urea was added), and the mixture was stirred at 60°C for 2 h. Then, 8 g of methyl methacrylate, 0.4 g of 2-bromoisobutyryl bromide, 0.4 g of ethylene glycol dimethacrylate, and 0.6 g of a catalyst (a mixture of copper bromide and 2,2'-bipyridine at a molar ratio of 1:3) were added, and the mixture was stirred at 90°C for 3 h under a nitrogen atmosphere. Finally, the product was obtained by precipitation, washing, and drying.

[0047] Preparation Example 4, a graphene / silica composite particle, differs from Preparation Example 1 only in that the graphene / silica composite particle is prepared according to the following method: Take 10 g of graphene / silica core-shell particles obtained in Preparation Example 1 and disperse them in a 10% by mass urea aqueous solution (urea is added in an amount of 1 g), stir and disperse at 60°C for 2 h, then add 9 g of methyl methacrylate, 0.4 g of 2-bromoisobutyryl bromide, 0.5 g of ethylene glycol dimethacrylate, and 0.7 g of an auxiliary agent (the auxiliary agent is a mixture of copper bromide and 2,2'-bipyridine in a molar ratio of 1:3), stir and react at 90°C under a nitrogen atmosphere for 3 h, and finally obtain by precipitation, washing, and drying.

[0048] Preparation Example 5, a graphene / silica composite particle, differs from Preparation Example 1 only in that the amount of methyl methacrylate added is 5 g.

[0049] Preparation Example 6, a graphene / silica composite particle, differs from Preparation Example 1 only in that the amount of methyl methacrylate added is 10 g.

[0050] Preparation Example 7, a graphene / silica composite particle, differs from Preparation Example 1 only in that ethylene glycol dimethacrylate is not added.

[0051] Preparation Example 8, a graphene composite particle, is prepared according to the following method: Disperse 10 g of single-layer graphene oxide (with a flake diameter of 0.5-5 μm and a thickness of 0.8-1.2 nm) in a 10% by mass urea aqueous solution (urea is added in an amount of 1 g), stir and disperse at 60°C for 2 h, then add 8 g of methyl methacrylate, 0.4 g of 2-bromoisobutyryl bromide, 0.4 g of ethylene glycol dimethacrylate, and 0.6 g of an auxiliary agent (the auxiliary agent is a mixture of copper bromide and 2,2'-bipyridine in a molar ratio of 1:3), stir and react at 90°C under a nitrogen atmosphere for 3 h, and finally obtain by precipitation, washing, and drying.

[0052] Example Example 1, a PU conveyor belt with a high wear-resistant surface layer, is prepared according to the following process steps: S1. Take 100 parts of polyether TPU (density 1140 kg / cm 3 , 6 parts of short carbon fibers (length 2-8 mm, fiber diameter 5-11 μm), 0.5 parts of graphene / silica composite particles prepared in Preparation Example 1, and 2 parts of antioxidant 1010, mix uniformly, and extrude and pelletize at 175-220°C to obtain a high wear-resistant surface layer masterbatch; S2. Qualitative heat treatment is performed on the polyester fiber woven skeleton fabric, wherein the linear diameter of the polyester fiber weft yarn is 0.25 mm, the density is 14 roots / cm, the linear diameter of the polyester fiber warp yarn is 1000D, the density is 18 roots / cm, and the control temperature is 170℃; S3. Polyurethane glue is coated on one side surface of the skeleton fabric, and drying is performed at 120℃; S4. Extrusion calendering is performed on the side of the skeleton fabric on which the polyurethane glue is coated, and the above-obtained high wear-resistant surface layer master batch is compounded to form a high wear-resistant surface layer, wherein the calendering temperature is 190℃, and the pressure is 12 Pa; S5. After the calendering compounding, cooling is performed to room temperature, and a PU conveying belt with a high wear-resistant surface layer is obtained.

[0053] Example 2, a PU conveying belt with a high wear-resistant surface layer, which is different from example 1 only in that the addition amount of the graphene / silicon dioxide composite particles prepared in preparation example 1 is 1 part.

[0054] Example 3, a PU conveying belt with a high wear-resistant surface layer, which is different from example 1 only in that the addition amount of the short carbon fiber is 4 parts.

[0055] Example 4, a PU conveying belt with a high wear-resistant surface layer, which is different from example 1 only in that the addition amount of the short carbon fiber is 8 parts.

[0056] Example 5, a PU conveying belt with a high wear-resistant surface layer, which is different from example 1 only in that the graphene / silicon dioxide composite particles prepared in preparation example 2 are used to replace the graphene / silicon dioxide composite particles prepared in preparation example 1.

[0057] Example 6, a PU conveying belt with a high wear-resistant surface layer, which is different from example 1 only in that the graphene / silicon dioxide composite particles prepared in preparation example 3 are used to replace the graphene / silicon dioxide composite particles prepared in preparation example 1.

[0058] Example 7, a PU conveying belt with a high wear-resistant surface layer, which is different from example 1 only in that the graphene / silicon dioxide composite particles prepared in preparation example 4 are used to replace the graphene / silicon dioxide composite particles prepared in preparation example 1.

[0059] Example 8, a PU conveying belt with a high wear-resistant surface layer, which is different from example 1 only in that the graphene / silicon dioxide composite particles prepared in preparation example 5 are used to replace the graphene / silicon dioxide composite particles prepared in preparation example 1.

[0060] Example 9, a PU conveying belt with a high wear-resistant surface layer, which is different from example 1 only in that the graphene / silicon dioxide composite particles prepared in preparation example 6 are used to replace the graphene / silicon dioxide composite particles prepared in preparation example 1.

[0061] Example 10, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 1 only in that 5 parts of polyborosiloxane are additionally added in the preparation of the high wear-resistant surface layer master batch.

[0062] Example 11, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 10 only in that the amount of polyborosiloxane added is 1 part.

[0063] Example 12, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 10 only in that the amount of polyborosiloxane added is 8 parts.

[0064] Comparative Example Comparative Example 1, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 1 only in that the amount of graphene / silica composite particles prepared in Preparation Example 1 added is 0.2 parts.

[0065] Comparative Example 2, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 1 only in that the amount of graphene / silica composite particles prepared in Preparation Example 1 added is 1.5 parts.

[0066] Comparative Example 3, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 1 only in that the graphene / silica composite particles prepared in Preparation Example 7 are used instead of the graphene / silica composite particles prepared in Preparation Example 1.

[0067] Comparative Example 4, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 1 only in that the graphene / silica composite particles prepared in Preparation Example 8 are used instead of the graphene / silica composite particles prepared in Preparation Example 1.

[0068] Comparative Example 5, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 1 only in that the graphene / silica core-shell particles prepared in Preparation Example 1 are used instead of the graphene / silica composite particles prepared in Preparation Example 1.

[0069] Comparative Example 6, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 1 only in that the graphene / silica composite particles prepared in Preparation Example 1 are replaced with an equal amount of single-layer graphene oxide.

[0070] Comparative Example 7, a PU conveyor belt with a high wear-resistant surface layer, differs from Example 1 only in that no graphene / silica composite particles prepared in Preparation Example 1 are added to the high wear-resistant surface layer master batch.

[0071] Performance detection test Mechanical property test: According to the relevant records in GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized or thermoplastic rubber", the tensile strength of the high wear-resistant surface layer master batch obtained in the examples and comparative examples was tested.

[0072] Wear resistance test: According to the relevant records in GB / T 9867-2008 "Determination of wear resistance of vulcanized or thermoplastic rubber", the wear resistance of the PU conveyor belt of the high wear-resistant surface layer obtained in the examples and comparative examples was tested.

[0073] Elasticity test: According to the relevant records in ASTM D395-2014 "Standard Test Methods for Rubber Properties-Compression Set", the compression permanent set of the high wear-resistant surface layer master batch obtained in the examples and comparative examples after 70℃, 24h was tested.

[0074] The above test results are shown in Table 1: Table 1 Performance test results According to Table 1, combined with Example 1 and Example 10, it can be seen that the performance of Example 10 is slightly improved compared with Example 1, and the reason is that the high wear-resistant surface layer of Example 10 also adds polyborosiloxane, which can improve the thermal stability of the surface layer material during the processing of the high wear-resistant surface layer master batch and the production process of the PU conveyor belt, reduce the tendency of the graphene / silica composite particles to aggregate outward, thereby effectively expanding the reinforcing effect of the composite particles, improving the dispersibility in the matrix material, and synergizing with the branched polymethyl methacrylate on the surface of the matrix material and the composite particles, enhancing the interfacial stress transfer, which is beneficial to improve the mechanical properties and wear resistance of the surface layer material and improve the long-term stability.

[0075] Combined with Example 1 and Comparative Example 3, it can be seen that the performance of Comparative Example 3 is lower than that of Example 1, and the reason is that the graphene / silica composite particles used in Comparative Example 3 are grafted with straight-chain polymethyl methacrylate on the surface, which has lower compatibility with the matrix TPU than branched polymethyl methacrylate, and the content of flexible chain segment is also reduced, which reduces the flexibility adjustment effect of the high wear-resistant surface layer and the anti-deformation ability.

[0076] Compared with Example 1, it can be seen from Example 1, Comparative Example 4 to Comparative Example 6 that the properties of Comparative Example 4 to Comparative Example 6 have obvious decline, the reason is that Comparative Example 4 uses modified graphene to replace graphene / silica composite particles, the shell protection effect of silica is lacked, the structure stability of the particles itself is decreased, and the particles are easy to agglomerate, leading to stress concentration, and the mechanical properties and wear resistance are decreased; in Comparative Example 6, unmodified graphene is directly added, the agglomeration tendency of graphene is more serious, and the performance is more obviously decreased; in Comparative Example 5, graphene / silica core-shell particles without modification by branched polymethyl methacrylate are used to replace the composite particles, and due to the dispersion of the rigid particles, the flexibility is decreased, the elasticity is reduced, and the compatibility between the particles and the matrix material is decreased, leading to the decrease of the wear resistance and the mechanical properties.

[0077] The above disclosure is only several specific embodiments of the present application, but the embodiments of the present application are not limited to this, and any changes that can be thought of by those skilled in the art should fall within the protection scope of the present application.

Claims

1. A PU conveyor belt with a high abrasion-resistant surface layer, characterized in that, It includes a reinforcing fabric and a highly abrasion-resistant surface layer; the highly abrasion-resistant surface layer comprises the following raw materials in parts by weight: 100 TPU units; 4-8 parts of short-cut carbon fiber; 0.5 to 1 part of graphene / silica composite particles; Antioxidant 1-3 parts; The graphene / silica composite particles have graphene as the core layer and silica as the shell layer; the surface of the graphene / silica composite particles is grafted with branched polymethyl methacrylate.

2. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 1, characterized in that, The raw materials for the graphene / silica composite particles include graphene / silica core-shell particles, methyl methacrylate, and branched monomers in a mass ratio of 1:(0.7-0.9):(0.03-0.05).

3. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 2, characterized in that, The raw materials for the graphene / silica core-shell particles include tetraethyl orthosilicate and graphene oxide in a mass ratio of 1:(0.015~0.02).

4. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 2, characterized in that, The branched monomers include one or more combinations of ethylene glycol dimethacrylate, p-divinylbenzene, p-vinyl methacrylate benzyl ester and 2-(diisopropylamino)ethyl methacrylate.

5. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 2, characterized in that, The graphene / silica composite particles were prepared according to the following method: Graphene / silica core-shell particles are dispersed in an aqueous urea solution and stirred at 60–65°C for 2–3 hours. Then, methyl methacrylate, initiator, branching monomer, and auxiliaries are added, and the mixture is stirred and reacted at 90–95°C under a nitrogen atmosphere for 2–3 hours. Finally, the product is obtained after precipitation, washing, and drying.

6. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 1, characterized in that, The chopped carbon fibers have a length of 2–8 mm and a fiber diameter of 5–11 μm.

7. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 1, characterized in that, The raw material for the high wear-resistant surface layer also includes 3 to 6 parts by weight of polyborosiloxane.

8. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 1, characterized in that, The TPU is a polyether-type TPU.

9. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 1, characterized in that, The raw materials for the skeleton fabric include one or more blends of cotton fiber, nylon fiber, and polyester fiber.

10. The PU conveyor belt with a high abrasion-resistant surface layer according to claim 1, characterized in that, The PU conveyor belt with the high abrasion-resistant surface layer is prepared according to the following process steps: S1. Weigh the raw materials for the high wear-resistant surface layer according to the corresponding mass fractions, mix them evenly, and then extrude and granulate to obtain the high wear-resistant surface layer masterbatch. S2. Perform qualitative heat treatment on the skeleton fabric, controlling the temperature at 160~190℃; S3. Coat one side of the skeleton fabric with polyurethane adhesive and dry at 120-140°C; S4. Extrusion and calendering are performed on the side of the skeleton fabric coated with polyurethane adhesive to form a high wear-resistant surface layer masterbatch, wherein the calendering temperature is 170-200℃ and the pressure is 10-15Pa. S5. After calendering and laminating, cool to room temperature to obtain a PU conveyor belt with a high wear-resistant surface layer.

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