Railway turnout base plate and preparation process thereof

Abstract

The invention belongs to the field of railway track accessories, and discloses a railway turnout base plate and a preparation process thereof, the railway turnout base plate comprises a rubber matrix, 25-35 parts of a composite reinforcing filler, 2-3 parts of a composite anti-aging agent and 2-3 parts of a composite vulcanizing agent; the rubber matrix is prepared from 50 to 60 parts of hydrogenated nitrile rubber, 20 to 30 parts of chloroprene rubber and 10 to 20 parts of ethylene-vinyl acetate copolymer; the composite reinforcing filler is prepared from 5 to 8 parts of surface modified graphene nanosheets, 10 to 15 parts of aramid short fibers and 10 to 12 parts of nano silicon dioxide; the problems that in the prior art, an existing turnout base plate is poor in abrasion resistance, insufficient in corrosion resistance, unreasonable in structure and imperfect in preparation technology are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of railway track accessories, in particular to a railway turnout pad and a preparation process thereof. BACKGROUND

[0002] The railway turnout is a key component in the railway track system, and the turnout pad, as a buffer connecting piece between the turnout and the sleeper, directly affects the safety and comfort of railway operation.

[0003] The existing turnout pad is mostly made of ordinary nitrile rubber or natural rubber, which has the following disadvantages: Firstly, the wear resistance is insufficient, and the pad is prone to wear and cracking after long-term impact and friction of the train wheelset; Secondly, the corrosion resistance is poor, and the pad is prone to aging and degradation in harsh environments such as humidity and salinity, thereby shortening the service life; Thirdly, the structural design is unreasonable, and the poor drainage leads to water immersion of the pad, thereby accelerating the corrosion; To solve the above problems, a rubber turnout pad with high strength, high wear resistance and excellent corrosion resistance is proposed, and the preparation process thereof is optimized to ensure stable and reliable product performance. SUMMARY

[0004] The present application aims to provide a railway turnout pad and a preparation process thereof to solve the problems of poor wear resistance, insufficient corrosion resistance, unreasonable structure and imperfect preparation process of the existing turnout pad.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: The technical scheme provided by the present application is: A railway turnout pad and a preparation process thereof, comprising a rubber matrix, further comprising 25-35 parts of a composite reinforcing filler, 2-3 parts of a composite antioxidant and 2-3 parts of a composite vulcanizing agent; The rubber matrix is composed of 50-60 parts of hydrogenated nitrile rubber, 20-30 parts of chlorobutyl rubber and 10-20 parts of ethylene-vinyl acetate copolymer; The composite reinforcing filler is composed of 5-8 parts of surface-modified graphene nanosheets, 10-15 parts of aramid short fibers and 10-12 parts of nanosilica; The upper surface of the pad body is provided with a honeycomb-shaped groove array, and the bottom is provided with a conical drainage hole, the large end of the conical drainage hole faces upward and communicates with the honeycomb-shaped groove; The surface-modified graphene nanosheet has a sheet diameter of 1-5 μm and a thickness of 1-5 nm; The aramid short fiber has a length of 1-3 mm; The nanosilica has a particle size of 20-50 nm.

[0006] Further, the composite antioxidant is composed of 1-1.5 parts of antioxidant MB and 1-1.5 parts of antioxidant ODA; The preparation method is as follows: antioxidant MB and antioxidant ODA are added into a double-screw mixer, and are melt-blended at 80-90℃ and a rotation speed of 300-400r / min for 15-20min; after cooling, they are crushed to 80-100 meshes to obtain the composite antioxidant.

[0007] Further, the composite vulcanizing agent is composed of 1.2-1.8 parts of insoluble sulfur, 0.5-0.8 parts of accelerator TMTD and 0.3-0.4 parts of accelerator DPG; The preparation method is as follows: the components are added into a planetary ball mill in proportion, zirconium oxide balls are used as grinding medium, the ball-to-material ratio is 5:1, and the rotation speed is 200-300r / min for 30-40min to obtain the composite vulcanizing agent.

[0008] Further, it further comprises 4-6 parts of environmentally friendly softener epoxy soybean oil and 2-4 parts of composite activator, which is composed of 1-2 parts of active zinc oxide and 1-2 parts of stearic acid; The preparation method of the composite activator is as follows: 1-2 parts of stearic acid is added into a stirring reaction kettle, heated and melted at 60-70℃, then 1-2 parts of active zinc oxide is added while stirring (rotation speed of 200-300r / min), and the stirring is continued for 15-20min to make the mixture uniform, then it is naturally cooled to room temperature to form a solid mixture, which is crushed to a particle size of 80-100 meshes by a crusher to obtain the composite activator.

[0009] Further, the preparation method of the surface-modified graphene nanosheet is as follows: graphene nanosheet is added into an ethanol solution of silane coupling agent KH550 with a mass fraction of 3-5%, ultrasonic dispersion is carried out for 30-40min (power of 300-400W), and then drying is carried out at 80-100℃ for 2-3h to obtain the surface-modified graphene nanosheet.

[0010] Further, the preparation method of the ethylene-vinyl acetate copolymer is as follows: ethylene monomer and vinyl acetate monomer are added into a high-pressure polymerization kettle in a molar ratio of (7-9):1, 0.05-0.1% of tert-butyl peroxyneopentanoate (C9H18O3) is added as an initiator, and 0.1-0.2% of n-butyl mercaptan is added as a molecular weight regulator; stirring is carried out at a pressure of 10-20MPa and a temperature of 150-200℃ for 2-3h, the reaction product is subjected to vacuum devolatilization to remove unreacted monomers, and then extrusion granulation and hot air drying at 80-90℃ for 1-2h are carried out to obtain the ethylene-vinyl acetate copolymer.

[0011] Further, the single groove of the honeycomb groove array is a regular hexagon with a side length of 5-8 mm, a depth of 4-6 mm, and a distance between adjacent grooves of 2-3 mm; the large end of the tapered drainage hole has a diameter of 8-10 mm, the small end has a diameter of 4-6 mm, and the distance between holes is 25-35 mm.

[0012] A preparation process of a railway turnout backing plate, comprising: S1: mixing: 50-60 parts of hydrogenated nitrile rubber, 20-30 parts of chlorobutyl rubber and 10-20 parts of ethylene-vinyl acetate copolymer are added to a mixer, plasticated at 90-100 DEG C and a rotation speed of 40-50 r / min for 4-6 min; 2-3 parts of a composite antioxidant, 4-6 parts of epoxy soybean oil and 2-4 parts of a composite activator are added and mixed at 85-95 DEG C for 3-4 min; 5-8 parts of surface modified graphene nanosheet, 10-15 parts of aramid short fiber and 10-12 parts of nano silicon dioxide are added and mixed at a temperature of 100-110 DEG C and a rotation speed of 50-60 r / min for 6-8 min; finally, 2-3 parts of a composite vulcanizing agent is added and mixed at 75-85 DEG C and a rotation speed of 30-40 r / min for 2-3 min, to obtain a mixed rubber; S2: vulcanization: the mixed rubber is pre-pressed into a sheet and placed in a mold preheated to 110-120 DEG C, and a segmented vulcanization process is adopted: first vulcanized at 150-160 DEG C and a pressure of 12-14 MPa for 6-8 min, then heated to 170-180 DEG C and vulcanized at a pressure of 14-16 MPa for 12-15 min, and after vulcanization, the mold is opened after pressure holding and cooling to below 80 DEG C, to obtain a vulcanized rubber blank; S3: post-treatment: the vulcanized rubber blank is processed by a laser engraving machine to form a honeycomb groove array, a drilling machine to form a tapered drainage hole, and finally dried by hot air at 80-100 DEG C for 2-3 h, to obtain a finished product.

[0013] Further, the pressure of the upper ram of the mixer in S1 is controlled at 0.7-0.9 MPa, and nitrogen protection is adopted during the mixing process.

[0014] Further, the temperature rising rate of the segmented vulcanization in S2 is 3-5 DEG C / min, and after vulcanization, secondary vulcanization treatment is performed: hot air vulcanization at 120-130 DEG C for 4-6 h.

[0015] The beneficial effects of the technical solution are: (1) The rubber matrix adopts hydrogenated nitrile rubber, chlorobutyl rubber and ethylene-vinyl acetate copolymer blending, the oil resistance and aging resistance of hydrogenated nitrile rubber are better than ordinary nitrile rubber, chlorobutyl rubber provides good weather resistance and flame retardance, and ethylene-vinyl acetate copolymer improves processing fluidity and elasticity, and the three synergistically improve the comprehensive performance of the matrix.

[0016] (2) In the composite reinforcing filler, the two-dimensional structure of the surface modified graphene nanosheet can be uniformly dispersed in the rubber matrix to form a dense reinforcing network, significantly improving the tensile strength and wear resistance; the high strength characteristics of aramid short fibers enhance the impact resistance; nano-silicon dioxide improves the hardness and wear resistance of the rubber, and the synergistic effect of the three greatly improves the mechanical properties of the pad plate.

[0017] (3) The honeycomb-shaped groove array design increases the contact area with the track, disperses the stress, and is beneficial to drainage; the large end of the conical drainage hole faces upward to facilitate the rapid flow of accumulated water, and the small end faces downward to accelerate drainage, avoiding corrosion caused by immersion of accumulated water. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A railway turnout pad and its preparation process are provided. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] The specific implementation process is as follows: Example 1 Please refer to Figure 1 A technical solution provided by the present application: a railway turnout pad and its preparation process, including component preparation: Rubber matrix: 500g hydrogenated nitrile rubber (acrylonitrile content 33%), 300g chlorobutyl rubber (CR2441), 200g ethylene-vinyl acetate copolymer (EVA18-3, VA content 18%); Composite reinforcing filler: 50g surface modified graphene nanosheet (flake diameter 1-3μm, thickness 1-3nm), 150g aramid short fiber (length 1-2mm, diameter 10μm), 100g nano-silicon dioxide (particle size 20-30nm, specific surface area 200m 2 / g); Composite antioxidant: 10g antioxidant MB (2-mercaptobenzimidazole), 10g antioxidant ODA; Composite vulcanizing agent: 12g insoluble sulfur (IS-60), 5g accelerator TMTD (tetramethylthiuram disulfide), 3g accelerator DPG (diphenyl guanidine); Epoxy soybean oil: 40g; Composite activator: 10g active zinc oxide (particle size 50nm), 10g stearic acid (octadecanoic acid); The components were prepared as follows: Composite antioxidant: twin-screw mixer 80℃, 300r / min melt blending for 15 min, and then crushed to 80 mesh after cooling; Composite vulcanizing agent: planetary ball mill (zirconia ball ratio 5:1) 200r / min mixing for 30 min; Surface modified graphene: 3% silane coupling agent KH550 ethanol solution ultrasonic dispersion for 30 min at 300W, and then dried at 80℃ for 2h; Ethylene-vinyl acetate copolymer: ethylene-vinyl acetate molar ratio 7:1, 0.05% tert-butyl peroxypivalate (C9H18O3) initiation, 0.1% n-butyl mercaptan adjustment, 10MPa, 150℃ reaction for 2h, and then dried at 80℃ for 1h after devolatilization and granulation; Composite activator: melt stearic acid at 60℃, and then add active zinc oxide under stirring at 200r / min, mix for 15 min, and then crushed to 80 mesh; The preparation process is as follows: S1: mixing: internal mixer 90℃, 40r / min, 0.7MPa plasticizing for 4 min; add composite antioxidant, epoxy soybean oil, and composite activator, mix at 85℃ for 3 min; add composite reinforcing filler, mix at 100℃, 50r / min for 6 min; add composite vulcanizing agent, mix at 75℃, 30r / min for 2 min (nitrogen protection), and then discharge glue at 90℃; S2: vulcanization: mold preheating at 110℃, temperature rising at 3℃ / min to 150℃, 12MPa vulcanization for 6 min, and then temperature rising to 170℃, 14MPa vulcanization for 12 min; pressure maintaining and cooling to 80℃ to open the mold, and then hot air secondary vulcanization at 120℃ for 4h; S3: post-processing: laser engraving honeycomb-shaped grooves (regular hexagon, side length 5mm, depth 4mm, and interval 2mm), and then drill conical drainage holes (large end 8mm, small end 4mm, and interval 25mm), and then hot air drying at 80℃ for 2h; Test item Test result Tensile strength 18.5 MPa Elongation at break 380% Shore A hardness 75 HA Akron abrasion amount 0.145 cm 3 / 1.61 km Volume change rate against salt water corrosion (5% NaCl, 72 h) 1.8% Compression set (70°C, 22 h) 18% Drainage rate (100 mL water) 12s In this embodiment, the amount of hydrogenated nitrile rubber 50 parts and graphene 5 parts is at the lower limit, the tensile strength is 18.5MPa, and the wear resistance is 0.145cm 3 / 1.61km, which is lower than the high ratio group, but meets the basic requirements of ordinary railway turnout; the high proportion of ethylene-vinyl acetate copolymer 20 parts improves the elongation at break by 380%, ensuring the cushioning performance of the pad; the design of honeycomb-shaped grooves and conical drainage holes makes the drainage rate reach 12s, effectively reducing water corrosion, and the volume change rate is 1.8%; the overall cost is low, and it is suitable for light load and low frequency operation scene.

[0021] Example 2: Please refer toFigure 1 The application provides a railway turnout backing plate and a preparation process thereof. Rubber matrix: 550 g of hydrogenated nitrile rubber, 250 g of chlorobutyl rubber and 150 g of ethylene-vinyl acetate copolymer; Composite reinforcing filler: 65 g of surface-modified graphene (2-4 μm in diameter and 2-4 nm in thickness), 125 g of aramid short fiber (1.5-2.5 mm in length) and 110 g of nano-silicon dioxide (30-40 nm in particle size and 250 m 2 / g in specific surface area); Composite antioxidant: 12.5 g of antioxidant MB and 12.5 g of antioxidant ODA; Composite vulcanizing agent: 15 g of insoluble sulfur, 6.5 g of accelerator TMTD and 3.5 g of accelerator DPG; Epoxy soybean oil: 50 g Composite activator: 15 g of active zinc oxide and 15 g of stearic acid; The components are prepared as follows: Composite antioxidant: 85 ℃, 350 r / min, blending for 17 min, and crushing to 90 mesh; Composite vulcanizing agent: 250 r / min, mixing for 35 min; Surface-modified graphene: 4% silane coupling agent KH550 solution, 350 W ultrasonic for 35 min, and 90 ℃ drying for 2.5 h; Ethylene-vinyl acetate copolymer: 8:1 in molar ratio, 0.075% initiator, 0.15% regulator, 15 MPa, 175 ℃ reaction for 2.5 h; Composite activator: 65 ℃, melt mixing for 17 min, and crushing to 90 mesh; The preparation process is as follows: S1: mixing: 95 ℃, 45 r / min, 0.8 MPa plasticizing for 5 min; 90 ℃ mixing for 3.5 min; 105 ℃, 55 r / min mixing for 7 min; 80 ℃, 35 r / min mixing for 2.5 min (nitrogen protection); S2: vulcanization: 115 ℃ preheating mold, 4 ℃ / min to 155 ℃, 13 MPa vulcanization for 7 min, and then 175 ℃, 15 MPa vulcanization for 13.5 min; 125 ℃ secondary vulcanization for 5 h; S3: post-treatment: groove side length 6.5 mm, depth 5 mm, interval 2.5 mm; drain hole large end 9 mm, small end 5 mm, interval 30 mm; 90 ℃ drying for 2.5 h; Test item Test result Tensile strength 22.3 MPa Elongation at break 350% Shore A hardness 78 HA Akron abrasion amount 0.098 cm 3 / 1.61 km Volume change rate against salt water corrosion 1.2% Compression set (70°C, 22 h) 12% Drainage rate (100 mL water) 10s The embodiment is an optimal proportioning scheme: 550 g of hydrogenated nitrile rubber and 150 g of ethylene-vinyl acetate copolymer balance strength and elasticity, the tensile strength reaches 22.3 MPa, the elongation at break is 350%, and the high-frequency impact of heavy-load trains can be borne; 65 g of graphene and 125 g of aramid fiber form a three-dimensional reinforcing network, the abrasion loss is reduced to 0.098 cm 3 / 1.61 km, the wear resistance is significantly improved; the volume change rate of the salt water corrosion resistance is only 1.2% and the compression permanent deformation is 12% due to the optimization of the amount of the composite antioxidant, which represents excellent fatigue resistance; the drainage rate of 10 s further reduces the corrosion risk, and the comprehensive performance is suitable for busy main line railway turnouts, and the cost performance is the highest.

[0022] Embodiment 3 Please refer to Figure 1 The application provides a technical scheme: a railway turnout pad and a preparation process thereof, which comprises component preparation. Rubber matrix: 600 g of hydrogenated nitrile rubber, 200 g of chlorobutyl rubber and 100 g of ethylene-vinyl acetate copolymer; Composite reinforcing filler: 80 g of surface-modified graphene (flake diameter 3-5 μm, thickness 3-5 nm), 100 g of aramid short fiber (length 2-3 mm) and 120 g of nano-silicon dioxide (particle size 40-50 nm, specific surface area 300 m 2 / g); Composite antioxidant: 15 g of antioxidant MB and 15 g of antioxidant ODA; Composite vulcanizing agent: 18 g of insoluble sulfur, 8 g of accelerator TMTD and 4 g of accelerator DPG; Epoxy soybean oil: 60 g; Composite activator: 20 g of active zinc oxide and 20 g of stearic acid; The components are prepared as follows: Composite antioxidant: 90 ℃, 400 r / min, blending for 20 min, and crushing to 100 meshes; Composite vulcanizing agent: 300 r / min, mixing for 40 min; Surface-modified graphene: 5% silane coupling agent KH550 solution, 400 W ultrasonic for 40 min, and 100 ℃ drying for 3 h; Ethylene-vinyl acetate copolymer: molar ratio 9:1, 0.1% initiator, 0.2% regulator, 20 MPa, 200 ℃ reaction for 3 h; Composite activator: 70 ℃, melt mixing for 20 min, and crushing to 100 meshes; The preparation process is as follows: S1: Mixing: 100℃, 50r / min, 0.9MPa plasticizing 6min; 95℃ mixing 4min; 110℃, 60r / min mixing 8min; 85℃, 40r / min mixing 3min (nitrogen protection); S2: Vulcanization: 120℃ preheating mold, 5℃ / min to 160℃, 14MPa vulcanization 8min, 180℃, 16MPa vulcanization 15min; 130℃ secondary vulcanization 6h; S3: Post-processing: groove side length 8mm, depth 6mm, spacing 3mm; drain hole large end 10mm, small end 6mm, spacing 35mm; 100℃ drying 3h; Test item Test result Tensile strength 25.1 MPa Elongation at break 320% Shore A hardness 82 HA Akron abrasion amount 0.078 cm 3 / 1.61 km Volume change rate against salt water corrosion 0.9% Compression set (70°C, 22 h) 10% Drainage rate (100 mL water) 9s This embodiment is a high-performance heavy-load adaptation scheme: a high proportion of 600g hydrogenated nitrile rubber makes the tensile strength reach 25.1MPa, the corrosion resistance is optimal (volume change rate 0.9%), and can withstand strong corrosive environments such as coastal areas and mining areas; the synergistic effect of 80g graphene and 120g nanosilica reduces the wear amount to 0.078cm 3 / 1.61km, the wear resistance reaches the optimal level; 6h secondary vulcanization further reduces the compression permanent deformation (10%), and the fatigue resistance is outstanding; but the low proportion of 100g ethylene-vinyl acetate copolymer reduces the elongation at break to 320%, the hardness increases to 82HA, and the component cost is higher, suitable for extreme working conditions such as heavy-load railways and metallurgical special lines.

[0023] Example 4: Please refer to Figure 1 , the present application provides a technical scheme: a railway turnout pad and its preparation process, including component preparation: Rubber matrix: 520g hydrogenated nitrile rubber, 280g chlorobutyl rubber, 200g ethylene-vinyl acetate copolymer; Composite reinforcing filler: 70g surface modified graphene (sheet diameter 1.5-3.5μm, thickness 1.5-3.5nm), 140g aramid short fiber (length 1-2.5mm), 105g nanosilica (particle size 25-35nm, specific surface area 220m 2 / g); Composite antioxidant: 11g antioxidant MB, 12g antioxidant ODA; Composite vulcanizing agent: 13g insoluble sulfur, 6g accelerator TMTD, 3.2g accelerator DPG; Epoxy soybean oil: 45g; Composite activator: 12g active zinc oxide, 13g stearic acid; The components are prepared as follows: Compound antioxidant: 82℃, 320r / min blending for 16min, and crushing to 85 mesh; Compound vulcanizing agent: 220r / min mixing for 32min; Surface modified graphene: 3.5% silane coupling agent KH550 solution 320W ultrasonic for 32min, and drying at 85℃ for 2.2h; Ethylene-vinyl acetate copolymer: molar ratio 7.5:1, 0.06% initiator, 0.12% regulator, 12MPa, 160℃ reaction for 2.2h; Compound activator: 62℃ melt mixing for 16min, and crushing to 85 mesh; The preparation process is as follows: S1: mixing: 92℃, 42r / min, 0.75MPa plasticizing for 4.5min; 88℃ mixing for 3.2min; 102℃, 52r / min mixing for 6.5min; 78℃, 32r / min mixing for 2.2min (nitrogen protection); S2: vulcanization: 112℃ preheating mold, 3.5℃ / min to 152℃, 12.5MPa vulcanization for 6.5min, and then 172℃, 14.5MPa vulcanization for 13min; 122℃ secondary vulcanization for 4.5h; S3: post-processing: groove side length 6mm, depth 4.5mm, interval 2.2mm; drain hole large end 8.5mm, small end 4.5mm, interval 28mm; drying at 85℃ for 2.2h; Test item Test result Tensile strength 20.2 MPa Elongation at break 390% Shore A hardness 73 HA Akron abrasion amount 0.122 cm 3 1.61 km Volume change rate against salt water corrosion 1.6% Compression set (70°C, 22 h) 15% Drainage rate (100 mL water) 11s This embodiment is designed for passenger-oriented medium-strength railway: 200g ethylene-vinyl acetate copolymer makes the elongation at break reach 390%, the Shore A hardness is 73HA, the buffer performance is optimal, and the passenger riding comfort can be improved; 70g graphene and 140g aramid fiber balance the strength (20.2MPa) and processing fluidity, the abrasion amount is 0.122cm 3 / 1.61km meets the medium operation frequency demand; the process parameters are moderate, suitable for continuous batch production; the corrosion volume change rate of 1.6% and the drainage rate of 11s ensure environmental adaptability, cost performance is outstanding, and can be widely applied to intercity railway turnout.

[0024] Comparative example 1: Please refer to Figure 1 , the application provides a comparative scheme: including component preparation: Rubber matrix: 800g ordinary butyronitrile rubber (NBR26, acrylonitrile content 26%), 200g chlorobutyl rubber, and the rest of the components and the amount are the same as those in example 2; The preparation process is as follows: the same as example 2; Test item Test result Tensile strength 14.8 MPa Elongation at break 280% Shore A hardness 70 HA Akron abrasion amount 0.265 cm 3 / 1.61 km Volume change rate against salt water corrosion 4.5% Compression set (70°C, 22 h) 25% Drainage rate (100 mL water) 10s The comparative example uses ordinary nitrile rubber instead of hydrogenated nitrile rubber and ethylene-vinyl acetate copolymer matrix, and the performance is significantly deteriorated: the tensile strength is only 14.8 MPa, the unsaturated bond in the molecular chain of ordinary NBR is easy to oxidize and degrade; the wear amount is 0.265 cm 3 / 1.61km, the wear resistance is insufficient; the salt water corrosion volume change rate is 4.5%, and cracking and bubbling are easy to occur during long-term use; the compression permanent deformation is 25%, the fatigue resistance is poor; and the drainage rate is only the same as that of example 2, which proves that the hydrogenated nitrile rubber and ethylene-vinyl acetate copolymer blended matrix is the core point of improving the comprehensive performance.

[0025] Comparative example 2: Please refer to Figure 1 , the application provides a comparative scheme: including component preparation: Composite reinforcing filler: 280g ordinary carbon black N330, instead of graphene, aramid and nano silicon dioxide in example 2; The rest of the components and the amount are the same as in example 2; The preparation process is as follows: the same as in example 2; Test item Test result Tensile strength 11.9 MPa Elongation at break 300% Shore A hardness 68 HA Akron abrasion amount 0.312 cm 3 / 1.61 km Volume change rate against salt water corrosion 3.8% Compression set (70°C, 22 h) 28% Drainage rate (100 mL water) 10s The comparative example uses ordinary carbon black instead of composite reinforcing filler, and the performance is the worst: the tensile strength is 11.9 MPa, the carbon black is a zero-dimensional filler, and cannot form a two-dimensional reinforcing network, so the reinforcing effect on the rubber matrix is limited; the wear amount is 0.312 cm 3 / 1.61km, the wear resistance is seriously insufficient, and the train is easy to fail quickly due to friction; the salt water corrosion volume change rate is 3.8%, the carbon black is not uniformly dispersed, and the corrosion medium penetration channel is easy to form; the compression permanent deformation is 28%, and the fatigue resistance is the worst; this result highlights the synergistic reinforcing advantage of the graphene, aramid and nano silicon dioxide composite reinforcing system, which is one of the keys of the application.

[0026] Comparative example 3: Please refer to Figure 1 , the application provides a comparative scheme: including component preparation: The same as in example 2; The preparation process is as follows: Mixing: no nitrogen protection, and the rest of the parameters are the same as in example 2; Vulcanization: 160℃, 14MPa single temperature vulcanization for 20min, no secondary vulcanization; Post-processing: the surface is a plane, the bottom is provided with a cylindrical drainage hole (diameter 6mm), and the rest is the same as in example 2; Test item Test result Tensile strength 17.6 MPa Elongation at break 310% Shore A hardness 72 HA Akron abrasion amount 0.185 cm 3 / 1.61 km Volume change rate against salt water corrosion 3.2% Compression set (70°C, 22 h) 22% Drainage rate (100 mL water) 25s The performance of the comparative example is greatly reduced due to the absence of process optimization and structure design: the oxidation degradation of rubber during mixing under the absence of nitrogen protection, the tensile strength is reduced to 17.6 MPa, which is 21.1% lower than that of example 2; the single vulcanization without secondary vulcanization results in insufficient vulcanization and uneven crosslinking density, and the compression permanent set is 22%; the planar structure cannot disperse stress, the cylindrical drainage hole has large drainage resistance, and the drainage rate is only 25 s, and the accumulated water causes the corrosion volume change rate to be 3.2%; the results prove the necessity of the nitrogen protection mixing, segmented vulcanization, secondary vulcanization process and honeycomb groove, tapered drainage hole structure for performance improvement, which constitutes another core point.

[0027] The multi-dimensional synergistic innovation of the rubber matrix, the reinforcing system, the preparation process and the structure design significantly breaks through the industry pain points of poor wear resistance, insufficient corrosion resistance and unstable performance of traditional rubber railway turnout pads. Through the systematic comparison of examples 1-4 and comparative examples 1-3, the present application discards the traditional single ordinary nitrile rubber matrix and adopts a ternary blending system of hydrogenated nitrile rubber (hydrogenated nitrile rubber), chlorobutyl rubber (CR) and ethylene-vinyl acetate copolymer (EVA). The high saturation of hydrogenated nitrile rubber gives excellent aging resistance and oil resistance, and the ethylene-vinyl acetate copolymer optimizes the processing fluidity and elasticity. The combination of the two and the weather resistance of chlorobutyl rubber (CR) forms a synergy. Compared with comparative example 1, the tensile strength of example 2 is increased by 50.7%, the salt water corrosion volume change rate is reduced by 73.3%, and the wear amount is reduced by 63%, fully proving the fundamental improvement of the creative combination of the ternary matrix on the performance. The present application constructs a multi-dimensional composite reinforcing network of surface modified graphene, aramid short fibers and nano silicon dioxide: the two-dimensional sheet structure of graphene forms a dense reinforcing skeleton, the high aspect ratio of aramid fiber enhances the impact resistance, and nano silicon dioxide optimizes the interface bonding. Compared with comparative example 2, the tensile strength of example 2 is increased by 87.4%, and the wear amount is reduced by 68.6%, highlighting the synergistic advantage of the reinforcing system.

[0028] In order to further illustrate the beneficial technical effects of the railway turnout pads and their preparation processes according to the embodiments of the present application, the railway turnout pads and their preparation processes according to examples 1-4 and comparative examples 1-3 are subjected to relevant performance tests; the test methods are as follows: Tensile strength and elongation at break test: cut the prepared pad sample into dumbbell-shaped samples, place them in a room temperature (23±2℃) and relative humidity (50±5)% environment for 24 hours, then use a tensile testing machine to perform axial tension on the samples at a speed of 500 mm / min, record the maximum tension at the moment of sample fracture, and calculate the tensile strength by combining the original cross-sectional area of the sample; at the same time, record the ratio of the elongation of the sample at the time of fracture to the original length to obtain the elongation at break.

[0029] Shore A hardness test: cut the sample into a flat test block with a thickness of not less than 6 mm, place it in a room temperature environment for 2 h, then vertically align the Shore A hardness tester indenter with the surface of the test block, ensure that the indenter is in full contact with the sample without tilting, apply pressure until the pointer is stable, read the hardness value after 10 s, test 5 times at different positions for each sample, and take the average value.

[0030] Akron abrasion amount test: process the sample into a standard abrasion test sample (diameter 16 mm, thickness 8 mm), install it on an Akron abrasion tester, make the sample contact with the grinding wheel, apply a load of 26.7 N, set the grinding wheel speed to 76 r / min, and the sample shaft speed to 34 r / min, remove the sample after 40 m of abrasion, clean the surface with anhydrous ethanol, dry and weigh, and calculate the abrasion amount according to the mass loss of the sample, the density and the abrasion distance.

[0031] Salt water corrosion volume change rate test: prepare a 5% by mass sodium chloride solution, process the sample into a 10 mm x 10 mm x 10 mm cube test sample, weigh and measure the initial volume by the drainage method; immerse the sample in the sodium chloride solution, seal and place it in a 25°C constant temperature oven for 72 h, then remove it, rinse the surface with distilled water, dry and measure the volume again, and calculate the volume change rate.

[0032] Compression permanent deformation test: process the sample into a cylindrical test sample with a diameter of 29 mm and a thickness of 12.5 mm, place it in a compression mold, compress it to 75% of the original thickness (compression rate 25%), then place the mold in a 70°C constant temperature oven for 22 h; remove it, unload the pressure, and measure the thickness after recovery at room temperature for 30 min, and calculate the compression permanent deformation rate.

[0033] Drainage rate test: build a test device (including a support, a funnel and a graduated cylinder), fix the sample horizontally below the funnel so that the drainage hole at the bottom of the sample is aligned with the upper opening of the funnel; measure 100 mL of distilled water with the graduated cylinder, quickly pour it into the honeycomb-shaped recess on the upper surface of the sample, start the stopwatch at the same time, and record the time when 100 mL of water completely flows into the graduated cylinder through the drainage hole, which is the drainage rate.

[0034] The above is only an embodiment of the present application, and well-known specific technical solutions or common knowledge of characteristics in the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent. The protection scope claimed in this application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A railway switch pad, characterized in that, The rubber matrix further comprises 25-35 parts of a composite reinforcing filler, 2-3 parts of a composite antioxidant and 2-3 parts of a composite vulcanizing agent; The rubber matrix is composed of 50-60 parts of hydrogenated nitrile rubber, 20-30 parts of chlorobutyl rubber and 10-20 parts of ethylene-vinyl acetate copolymer; The composite reinforcing filler is composed of 5-8 parts of surface-modified graphene nanosheets, 10-15 parts of aramid short fibers and 10-12 parts of nano-silica; The upper surface of the base plate body is provided with a honeycomb-shaped groove array, and the bottom is provided with a tapered drainage hole, the large end of the tapered drainage hole faces upward and communicates with the honeycomb-shaped groove; The surface-modified graphene nanosheet has a sheet diameter of 1-5 μm and a thickness of 1-5 nm; The aramid short fiber has a length of 1-3 mm; The nano-silica has a particle size of 20-50 nm.

2. The railway switch tie plate of claim 1, wherein, The composite antioxidant is composed of 1-1.5 parts of antioxidant MB and 1-1.5 parts of antioxidant ODA; The preparation method comprises the following steps: adding the antioxidant MB and the antioxidant ODA into a double-screw mixer, melt blending at 80-90 ℃ and a rotation speed of 300-400 r / min for 15-20 min, and then crushing to 80-100 mesh after cooling to obtain the composite antioxidant.

3. The railway switch tie plate of claim 1, wherein, The composite vulcanizing agent is composed of 1.2-1.8 parts of insoluble sulfur, 0.5-0.8 parts of accelerator TMTD and 0.3-0.4 parts of accelerator DPG; The preparation method comprises the following steps: adding the components into a planetary ball mill, using zirconia balls as grinding medium, mixing at a ball-to-material ratio of 5:1 and a rotation speed of 200-300 r / min for 30-40 min to obtain the composite vulcanizing agent.

4. The railway switch tie plate of claim 1, wherein, Further comprising 4-6 parts of an environmentally-friendly softener, epoxy soybean oil, and 2-4 parts of a composite activator, which is composed of 1-2 parts of active zinc oxide and 1-2 parts of stearic acid; The preparation method of the composite activator comprises the following steps: adding 1-2 parts of stearic acid into a stirring reaction kettle, heating and melting at 60-70 ℃, then adding 1-2 parts of active zinc oxide while stirring (at a rotation speed of 200-300 r / min), continuously stirring for 15-20 min to make the mixture uniform, then naturally cooling to room temperature to form a solid mixture, and then crushing to a particle size of 80-100 mesh by a crusher to obtain the composite activator.

5. The railway switch tie plate of claim 1, wherein, The preparation method of the surface-modified graphene nanosheet comprises the following steps: adding graphene nanosheets into an ethanol solution of silane coupling agent KH550 with a mass fraction of 3-5%, ultrasonic dispersing for 30-40 min (at a power of 300-400 W), and then drying at 80-100 ℃ for 2-3 h to obtain the surface-modified graphene nanosheet.

6. The railway switch tie plate of claim 1, wherein, The preparation method of the ethylene-vinyl acetate copolymer is as follows: ethylene monomers and vinyl acetate monomers are added into a high-pressure polymerization kettle in a molar ratio of (7-9):1, 0.05-0.1% of tert-butyl peroxy neopentanoate (C9H18O3) is added as an initiator, and 0.1-0.2% of n-butyl mercaptan is added as a molecular weight regulator; under the conditions of a pressure of 10-20 MPa and a temperature of 150-200 ℃, the reaction is stirred for 2-3 h, the reaction product is subjected to pressure reduction and devolatilization to remove unreacted monomers, and then extrusion granulation, hot air drying at 80-90 ℃ for 1-2 h are performed to obtain the ethylene-vinyl acetate copolymer.

7. The railway switch tie plate of claim 1, wherein The single groove of the honeycomb groove array is a regular hexagon with a side length of 5-8 mm and a depth of 4-6 mm, and the distance between adjacent grooves is 2-3 mm; the large end of the tapered drainage hole has a diameter of 8-10 mm, the small end has a diameter of 4-6 mm, and the distance between holes is 25-35 mm.

8. A process for the production of a mat according to any one of claims 1 to 7, characterised in that, Comprising: S1: mixing: 50-60 parts of hydrogenated nitrile rubber, 20-30 parts of chlorobutyl rubber and 10-20 parts of ethylene-vinyl acetate copolymer are added to a mixer, plasticized at 90-100 ℃ and a rotation speed of 40-50 r / min for 4-6 min; 2-3 parts of a composite antioxidant, 4-6 parts of epoxy soybean oil and 2-4 parts of a composite activator are added and mixed at 85-95 ℃ for 3-4 min; 5-8 parts of surface-modified graphene nanosheet, 10-15 parts of aramid short fiber and 10-12 parts of nano silicon dioxide are added and mixed at a temperature of 100-110 ℃ and a rotation speed of 50-60 r / min for 6-8 min; finally, 2-3 parts of a composite vulcanizing agent is added and mixed at 75-85 ℃ and a rotation speed of 30-40 r / min for 2-3 min to obtain a mixed rubber; S2: vulcanization: the mixed rubber is pre-pressed into a sheet and placed in a mold preheated to 110-120 ℃, and a staged vulcanization process is adopted: first vulcanized at 150-160 ℃ and a pressure of 12-14 MPa for 6-8 min, then heated to 170-180 ℃ and vulcanized at a pressure of 14-16 MPa for 12-15 min, and after vulcanization, the mold is opened after pressure holding and cooling to below 80 ℃ to obtain a vulcanized rubber blank; S3: post-treatment: the vulcanized rubber blank is processed into a honeycomb groove array by a laser engraving machine and a tapered drainage hole by a drilling machine, and finally dried by hot air at 80-100 ℃ for 2-3 h to obtain a finished product.

9. The manufacturing process of claim 8, wherein, The upper ram pressure of the mixer in S1 is controlled at 0.7-0.9 MPa, and nitrogen protection is adopted during the mixing process.

10. The manufacturing process of claim 8, wherein, In S2, the temperature rising rate of the staged vulcanization is 3-5 ℃ / min, and after the vulcanization is completed, a secondary vulcanization treatment is performed: hot air vulcanization at 120-130 ℃ for 4-6 h.

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