Damping rubber composition for track fastener and preparation method of damping rubber composition

Abstract

The invention discloses a damping rubber composition for a track fastener and a preparation method thereof. The damping rubber is characterized by being prepared from the following raw materials in parts by weight: 100 parts of composite rubber, 25-35 parts of damping particles, 15-20 parts of sheet structure filler, 5-10 parts of a plasticizer, 5-10 parts of a tackifier, 3-5 parts of high-temperature-resistant fibers, 2-4 parts of a vulcanizing agent, 3-5 parts of an activating agent, 2-2.5 parts of an accelerant and 1-3 parts of an anti-aging agent, the composite rubber is a compound of ethylene propylene diene monomer, natural rubber and nitrile rubber; the damping particles are elastic particles obtained by filling aerogel nanopores with asphalt and a glycidyl methacrylate modified elastomer. The damping particles are dispersed in a rubber system, the activity capacity of a rubber molecular chain is enhanced, remarkable internal friction is generated to consume energy and generate hysteresis deformation, and the damping particles are used for an elastic cushion of a track fastener and have excellent damping performance, ageing resistance and load impact fatigue resistance.

Description

Technical Field

[0001] The invention relates to the technical field of rail transit, and in particular to a damping rubber composition for rail fasteners and a preparation method thereof. Background Art

[0002] With the rapid development of rail transit, higher technical requirements have been put forward for track structures and related components of the supporting chain. In particular, high-speed rail and heavy-load trains not only require the track to provide sufficient support capacity, but also require excellent shock absorption and vibration isolation performance. On the one hand, high-performance shock absorption can reduce the noise and vibration generated during train operation and improve passenger comfort; on the other hand, high-performance shock absorption can prevent fatigue of the train under long-term repeated load stress, ensuring the life and operation safety of high-speed trains.

[0003] Rail fasteners are important components for fixing rails and sleepers, and rail elastic pads are important elastic components of the rail fastener system. The rail rubber pads used in the fastener system provide important support for the smooth and safe operation of the train. During the operation of the train, the track needs to withstand huge pressure and frequent alternating impacts. The fastener elastic pads have high elasticity and good damping and shock absorption performance, which can effectively buffer the impact force between the rails and sleepers, improve the stability and comfort of train operation, extend the service life of the track, and reduce the frequency of maintenance and replacement.

[0004] At present, the elastic pads of rail fasteners have been widely used in rail transportation such as high-speed railways, heavy-load railways, and urban rails. In particular, the ballastless track that is gradually becoming popular now has its track system's shock absorption protection all provided by the elastic pads of the fasteners, which puts forward higher requirements on the elastic pads' aging resistance, long-term service performance, high-load damping performance, and effective damping temperature range.

[0005] According to the technical requirements of the existing rail fastener elastic pads, in accordance with GB / T21527-2008 "Rail Transit Fastener System Elastic Pads", EPDM rubber is usually used to make pads, which can better absorb vibration energy. However, with the requirements for high-level vibration reduction, the damping performance of single EPDM rubber is limited, and it is prone to aging, cracking and other problems during long-term use, resulting in a gradual decline in shock absorption and vibration isolation performance. The invention patent with publication number CN107337814B discloses a high-damping rubber material, which improves the formation of weak bonds by using hindered phenols and hindered amines, thereby improving the damping performance of the rubber material; and uses lamellar fillers to form a barrier effect on external heat, oxygen, and ozone, thereby avoiding the aging of the rubber material. The publication number CN106543510B discloses a high-damping rubber material and a preparation method thereof, which introduces multiple hydrogen bond units or metal ligands into the molecular chain of the rubber, and utilizes multiple hydrogen bonds and metal coordination bonds to reversibly break and regenerate, thereby dissipating energy and improving the damping performance of the rubber.

[0006] Although the existing technology has improved the damping performance of rubber, its effective damping temperature range is relatively narrow, and its fatigue resistance and mechanical properties under high loads still have major defects. In order to further improve the damping performance of rail fastener elastic pads, improve the smoothness of train operation, and improve high-load impact resistance and fatigue resistance, the proposed relevant group standard T∕ZZB 1443-2019 "Rail Fastener Underrail (Rubber Composite) Pad" puts forward higher technical requirements for the comprehensive performance of rail rubber pads. Summary of the invention

[0007] In order to improve the damping effect and load impact fatigue resistance of rubber for rail fasteners, the present invention discloses a damping rubber for rail fasteners. The rubber is improved by damping particles. When used for the pad of the rail fastener, the damping rubber has good mechanical properties and the ability to resist rapid impact loads; the effective damping temperature range is broadened, and the better damping performance effectively absorbs and alleviates the impact caused by high-speed vibration, thereby maintaining the stability of the train.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a damping rubber for rail fasteners, which is characterized in that it comprises the following raw materials measured by weight: 100 parts of composite rubber, 25-35 parts of damping particles, 15-20 parts of sheet structure filler, 5-10 parts of plasticizer, 5-10 parts of tackifier, 3-5 parts of high temperature resistant fiber, 2-4 parts of vulcanizer, 3-5 parts of activator, 2-2.5 parts of accelerator, and 1-3 parts of antioxidant; wherein:

[0010] The composite rubber is a composite of EPDM rubber, natural rubber and nitrile rubber;

[0011] The damping particles are elastic particles obtained by filling aerogel nanopores with asphalt and glycidyl methacrylate modified elastomer.

[0012] Preferably, the composite rubber is a composite of EPDM rubber, natural rubber, and nitrile rubber in a mass ratio of 10:(3-8):(1-2). EPDM rubber has excellent high and low temperature resistance, can maintain good elasticity regardless of high or low temperatures, and has excellent ozone and UV resistance, which can meet the requirements of long-term outdoor use; natural rubber has excellent elasticity, tensile strength, and wear resistance, and assists the rubber in improving damping performance; nitrile rubber has excellent heat resistance and a high glass transition temperature, and assists the rubber in improving rebound performance at high temperatures. The damping temperature range is broadened by the composite rubber, thereby maintaining a stable damping effect in a wider temperature range material.

[0013] Preferably, the damping particles are elastic particles obtained by filling aerogel nanopores with a viscoelastic body formed by blending asphalt with a glycidyl methacrylate modified elastomer; wherein the aerogel is at least one of silica aerogel, alumina aerogel, and polyimide aerogel.

[0014] Further preferably, the porosity of the aerogel is greater than 75% and the pore size is less than 100nm. Particularly preferably, the pore size of the aerogel is less than 50nm. Aerogel has a rich nanoporous structure, and when used in rubber, it will form rich micropores. The nanopores can effectively absorb the energy generated by vibration, thereby reducing the vibration generated by the structure. The present invention obtains elastic particles (i.e., damping particles) by pre-filling the aerogel nanopores with asphalt and glycidyl methacrylate modified elastomer after blending. Most of the asphalt and glycidyl methacrylate modified elastomer are adsorbed in the nanopores of the aerogel, forming a distribution form similar to that of nanocapsules. When the damping particles are dispersed in the rubber system, the asphalt / glycidyl methacrylate modified elastomer blend in the nanopores of the aerogel exhibits excellent viscoelasticity, which can effectively dissipate the energy generated by rubber vibration, reduce vibration noise, and significantly improve the damping performance of the rubber. The excellent interface ability of the aerogel increases the dispersion interface of the damping particles in the rubber, forms a dispersion similar to that of nanocapsules, increases the contact interface, and increases the internal friction of the material to lose energy. Viscoelastic damping particles have the characteristics of both viscoelastic energy dissipation and elastic energy storage. When subjected to external force, they will produce hysteresis deformation, dissipate energy instantly, and play a role in vibration reduction.

[0015] More preferably, the damping particles are formed by blending asphalt with glycidyl methacrylate modified elastomer to form a viscoelastic body and aerogel in a volume ratio of 2:(3-4), and the viscoelastic body is pre-filled in the nano-pores of the aerogel by hot melting.

[0016] More preferably, the viscoelastic body is compounded by asphalt and glycidyl methacrylate modified elastomer in a mass ratio of 10:(2-5). Asphalt is a non-Newtonian fluid. When the aerogel is used to fill rubber, its ability to resist deformation increases when the impact or load increases, and it has more efficient energy absorption and buffering effect. Particularly preferably, the asphalt is 70# or 90# asphalt, which has a lower kinematic viscosity and excellent high-load impact resistance.

[0017] Preferably, the glycidyl methacrylate modified elastomer is a glycidyl methacrylate (GMA) modified elastomer, such as the commercial GMA modified vinyl elastomer Fine-Blend® SOG-03. By introducing polar groups, the damping particles are evenly dispersed in the rubber matrix, the effective damping temperature range is broadened, and the damping performance is increased. Further preferably, the glycidyl methacrylate modified elastomer is at least one of a GMA modified thermoplastic polyester elastomer, a GMA modified thermoplastic polyurethane elastomer, a GMA modified styrene-butadiene-styrene triblock copolymer, a GMA modified ethylene acrylic acid copolymer, and a GMA modified ethylene-vinyl acetate copolymer.

[0018] Preferably, the sheet structure filler is at least one of mica powder, kaolin, montmorillonite and pyrophyllite. By dispersing the layered inorganic matter, the internal friction of the rubber material is increased to dissipate energy, thereby achieving the effect of absorbing energy and reducing vibration, and preventing aging.

[0019] Preferably, the plasticizer is at least one of pine tar oil, dioctyl phthalate, and aromatic oil.

[0020] Preferably, the tackifier is at least one of coumarone resin, rosin resin, alkylphenolic resin, petroleum resin, and terpene resin. The tackifier has the functions of softening, reinforcing, plasticizing, tackifying, and dispersing in rubber. It can enhance the adhesion between rubber and fiber and filler and improve the uniformity of rubber extrusion.

[0021] Preferably, the high temperature resistant fiber is ceramic fiber, glass fiber or polymer fiber that can withstand a temperature higher than 190°C for a long time. The polymer fiber that can withstand a temperature higher than 190°C for a long time is preferably at least one of polyphenylene sulfide fiber and polytetrafluoroethylene fiber. The fiber can effectively enhance the tensile strength and stiffness of the rubber, enabling it to withstand greater tension and pressure and maintain good damping properties. The polymer fiber that can withstand a temperature higher than 190°C for a long time is selected to ensure that the fiber will not be damaged during high temperature vulcanization.

[0022] Further preferably, the high temperature resistant fiber is a fiber with a diameter of 10-20 μm and a length of 3-6 mm.

[0023] Preferably, the vulcanizing agent is sulfur.

[0024] Preferably, the activator is at least one of zinc oxide, stearic acid, zinc carbonate and magnesium oxide; the activator is dispersed in the rubber to mainly assist in the later vulcanization molding, enhance the vulcanization activity, accelerate the vulcanization reaction and shorten the vulcanization time.

[0025] Preferably, the accelerator is selected from at least one of CZ (N-cyclohexyl-2-benzothiazole sulfenamide), TBBS (N-tert-butyl-2-benzothiazole sulfenamide), NOBS (N-oxydiethylene-2-benzothiazole sulfenamide), DZ (N,N'-dicyclohexyl-2-benzothiazole sulfenamide, TMTD (tetramethylthiuram disulfide), TMTM (tetramethylthiuram monosulfide), TETD (tetraethylthiuram disulfide), DPTT (pentamethylenethiuram hexasulfide), ZDC (zinc diethyldithiocarbamate), BZ (zinc dibutyldithiocarbamate), and PZ (zinc dimethyldithiocarbamate); the addition of the accelerator accelerates the cross-linking reaction between the vulcanizing agent and the rubber molecules during vulcanization molding, thereby achieving the effect of shortening the vulcanization time and reducing the vulcanization temperature.

[0026] Preferably, the antioxidant is selected from antioxidant RD, antioxidant NBC, and antioxidant DNP in a mass ratio of 10:(3-5):(2-3). Antioxidant RD has multiple effects of anti-oxidation, anti-ozone, anti-heat aging and anti-hydrolysis; antioxidant NBC has air aging resistance; antioxidant DNP has heat and oxygen aging resistance, and it can absorb and neutralize free radicals in the environment, thereby preventing the free radicals from damaging the material and preventing heat and oxygen aging. The synergistic effect can effectively delay rubber aging and extend the service life of rubber.

[0027] The present invention also provides a method for preparing the damping rubber for rail fasteners, wherein the specific preparation method is as follows:

[0028] S1. The asphalt and the glycidyl methacrylate modified elastomer are mixed evenly, added to the co-rotating twin-screw extruder for hot melt extrusion; a feeding port is set in the fifth section of the co-rotating twin-screw extruder, and aerogel is continuously added according to volume measurement by a loss-in-weight scale, and the aerogel micropores adsorb the completely hot-melt asphalt and glycidyl methacrylate modified elastomer, and extruded into sheets through a die to obtain damping particles;

[0029] S2. Add 100 parts of composite rubber, 5-10 parts of plasticizer and 5-10 parts of tackifier into an internal mixer and mix for 3-5 minutes, then add 25-35 parts of damping particles, 10-15 parts of sheet structure filler, 3-5 parts of high temperature resistant fiber, 3-5 parts of activator and 1-3 parts of antioxidant and continue mixing for 5-8 minutes, and control the rotor temperature of the internal mixer to be lower than 120°C; put the rubber material into an open mixer, and control the roller temperature of the open mixer to 50-60°C with circulating cooling water in the roller. When the rubber material forms a continuous roll, add 2-4 parts of vulcanizer and 2-2.5 parts of accelerator, make a triangle package 3-5 times, and then thinly pass 3 times to evenly disperse the material before unrolling to obtain a damping rubber composition for rail fasteners.

[0030] For the damping rubber composition, when it is used to make elastic pads for rail fasteners, the operating process is as follows: add the damping rubber composition to a pin-type cold feed extruder, control the screw temperature: zone 1 temperature 65°C, zone 2 temperature 60°C, zone 3 temperature 55°C, head temperature 70°C; the rubber material is homogenized and kneaded by segmentation and shearing by multiple pins on the screw, and different die openings are set at the die opening to obtain a sheet-like rubber blank with a thickness of 2-16mm, place it on a louver car for 4-24h, cut it and place it in a mold, and vulcanize it for 10-15min at a pressure of 10-15MPa and a temperature of 170°C-180°C to obtain an elastic pad for rail fasteners.

[0031] Compared with the prior art, the damping rubber composition and preparation method for rail fasteners of the present invention have the following beneficial effects:

[0032] 1. The present invention creatively blends asphalt and glycidyl methacrylate modified elastomer and pre-fills the aerogel nanopores to obtain damping particles, and disperses the damping particles in the rubber system. On the one hand, the nanostructure and high interface of the aerogel enable the asphalt / glycidyl methacrylate modified elastomer to be dispersed in the rubber system in the form of nano-microcapsules, thereby enhancing the mobility of the rubber molecular chains. When subjected to external forces, significant internal friction will be generated to dissipate energy and cause hysteresis deformation, thereby playing a vibration reduction role. On the other hand, the asphalt / glycidyl methacrylate modified elastomer is filled in the nanostructure of the aerogel, which can prevent heat and oxygen aging, thereby ensuring the long life of the rubber pad and long-term damping stability.

[0033] 2. The present invention compounds EPDM rubber, natural rubber and nitrile rubber to broaden the damping temperature range, thereby maintaining a stable damping effect in a wider temperature range material.

[0034] 3. The present invention promotes the rubber to have good mechanical properties and dynamic viscoelastic behavior through the synergy of damping particles, sheet structure fillers and high temperature resistant fibers, and has excellent deformation resistance and impact fatigue resistance under track alternating loads; at the same time, it maintains excellent damping performance to reduce vibration amplitude and improve the stability and comfort of the system.

[0035] 4. The technology of the present invention is easy to implement on a large scale, and the equipment and raw materials used are all conventionally available raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 tanδ-T is a graph showing the relationship between the damping factor and temperature of the samples of Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to further understand the technical means, technical objectives and technical effects achieved by the present invention, the present invention is described in detail below in conjunction with the embodiments. For raw materials, equipment and processes for which technical parameters are not indicated, they are all conventional choices in the art.

[0038] Technical parameters of some raw materials and equipment used in the implementation plan:

[0039] EPDM rubber: brand EPDM 722P, ethylene content 70%, Mooney viscosity [ML (1+4) 125℃] 20MU, Dow, USA.

[0040] Glycidyl methacrylate modified elastomer: GMA modified vinyl elastomer, model Fine-Blend® SOG-03, GMA functional group content 2.0-3.0%, provided by Jiayirong Polymer (Shanghai) Co., Ltd.

[0041] Silica aerogel: Porosity greater than 90%, pore size 25-45nm.

[0042] Parallel co-rotating twin-screw extruder: Model SJWA-65, screw diameter Φ65mm, L / D=44, Changzhou JWELL Intelligent Chemical Equipment Co., Ltd.

[0043] Pin-type cold feed extruder: Model XJD-65, screw diameter Φ65mm, aspect ratio 12:1, Changzhou Daban Machinery Co., Ltd.

[0044] Double-roll mixing mill: Model XK-660, Qingdao Junlin Machinery Co., Ltd.

[0045] Example 1

[0046] S1. 70# asphalt and GMA modified vinyl elastomer SOG-03 are mixed uniformly at a mass ratio of 10:2, added into a parallel co-rotating twin-screw extruder for hot melting to form a viscoelastic body, and the extrusion temperature of each zone of the screw is controlled as follows: 90°C in zone 1; 100°C in zone 2; 120°C in zone 3; 140°C in zone 4; 150°C in zone 5; 130°C in zone 6; 120°C in zone 7; 120°C in zone 8; 110°C in zone 9; 110°C in zone 10; a feeding port is set in the fifth zone of the parallel co-rotating twin-screw extruder, and the viscoelastic body and the silica aerogel are compounded in a volume ratio of 2:3, and the silica aerogel is continuously added according to the volume measurement by a weight loss scale, and the completely hot-melted asphalt and the GMA modified vinyl elastomer SOG-03 are adsorbed by the micropores of the silica aerogel, and extruded into sheets through a die to obtain damping particles;

[0047] S2. Prepare composite rubber with EPDM rubber, natural rubber and nitrile rubber in a mass ratio of 10:3:2, add 100 parts of composite rubber, 6 parts of aromatic oil plasticizer and 5 parts of coumarone resin tackifier into an internal mixer and mix for 5 minutes, then add 25 parts of damping particles, 15 parts of mica powder, 5 parts of glass fiber (diameter 10 μm, length 5 mm), 3 parts of zinc oxide activator and 2 parts of antioxidant (antioxidant RD, antioxidant NBC and antioxidant DNP are compounded in a mass ratio of 10:5:3) and continue mixing for 5 minutes, and control the rotor temperature of the internal mixer to be lower than 120°C; put the rubber compound into an open mixer, and control the roller temperature of the open mixer to 50-60°C with circulating cooling water in the roller, and when the rubber compound forms a continuous roll, add 2.5 parts of sulfur and 2 parts of TMTD accelerator, make a triangle roll 4 times, and then thinly pass 3 times to evenly disperse the material before unrolling to obtain a damping rubber composition for rail fasteners.

[0048] Example 2

[0049] S1. Mix 70# asphalt and GMA-modified thermoplastic polyurethane elastomer in a mass ratio of 10:3, add them into a parallel co-rotating twin-screw extruder to heat-melt them into a viscoelastic body, and control the extrusion temperature of each zone of the screw as follows: 90°C in zone 1; 120°C in zone 2; 130°C in zone 3; 140°C in zone 4; 155°C in zone 5; 140°C in zone 6; 130°C in zone 7; 120°C in zone 8; 110°C in zone 9; 110°C in zone 10; set a feeding port in the fifth zone of the parallel co-rotating twin-screw extruder, and according to the composite measurement of the viscoelastic body and the silica aerogel in a volume ratio of 2:4, continuously add the silica aerogel according to the volume measurement by a loss-in-weight scale, and the silica aerogel micropores adsorb the completely hot-melted asphalt and the GMA-modified thermoplastic polyurethane elastomer, and extrude them into sheets through a die to obtain damping particles;

[0050] S2. Prepare composite rubber with EPDM rubber, natural rubber and nitrile rubber in a mass ratio of 10:8:2, add 100 parts of composite rubber, 5 parts of aromatic oil plasticizer and 8 parts of terpene resin tackifier into an internal mixer and mix for 3 minutes, then add 30 parts of damping particles, 18 parts of mica powder, 5 parts of glass fiber (diameter 10 μm, length 5 mm), 5 parts of zinc oxide activator and 1 part of antioxidant (antioxidant RD, antioxidant NBC and antioxidant DNP are compounded in a mass ratio of 10:3:3) and continue mixing for 8 minutes, and control the rotor temperature of the internal mixer to be lower than 120°C; put the rubber compound into an open mill, and control the roller temperature of the open mill to 50-60°C with circulating cooling water in the roller, and when the rubber compound forms a continuous roll, add 2.8 parts of sulfur and 2 parts of DZ accelerator, make a triangle roll 5 times, and then thinly pass 3 times to evenly disperse the material before unrolling to obtain a damping rubber composition for rail fasteners.

[0051] Example 3

[0052] S1. 120# asphalt and GMA modified vinyl elastomer SOG-03 were mixed uniformly at a mass ratio of 10:2, added to a parallel co-rotating twin-screw extruder for hot melting to form a viscoelastic body, and the extrusion temperature of each zone of the screw was controlled as follows: 90°C in zone 1; 100°C in zone 2; 120°C in zone 3; 140°C in zone 4; 150°C in zone 5; 130°C in zone 6; 120°C in zone 7; 120°C in zone 8; 110°C in zone 9; 110°C in zone 10; a feeding port was set in the fifth section of the parallel co-rotating twin-screw extruder, and the viscoelastic body and silica aerogel were compositely measured at a volume ratio of 2:3, and silica aerogel was continuously added according to volume measurement by a weight loss scale, and the silica aerogel micropores adsorbed the completely hot-melted asphalt and GMA modified vinyl elastomer SOG-03, and extruded into sheets through a die to obtain damping particles;

[0053] S2. Prepare composite rubber with EPDM rubber, natural rubber and nitrile rubber in a mass ratio of 10:4:2, add 100 parts of composite rubber, 10 parts of pine tar plasticizer and 5 parts of rosin resin tackifier into an internal mixer and mix for 5 minutes, then add 35 parts of damping particles, 20 parts of pyrophyllite, 5 parts of polyphenylene sulfide fiber (diameter 10 μm, length 3 mm), 3 parts of stearic acid activator and 2 parts of antioxidant (antioxidant RD, antioxidant NBC and antioxidant DNP are compounded in a mass ratio of 10:5:2) and continue mixing for 8 minutes, and control the rotor temperature of the internal mixer to be lower than 120°C; put the rubber compound into an open mill, and control the roller temperature of the open mill to 50-60°C with circulating cooling water in the roller, and when the rubber compound forms a continuous roll, add 2.5 parts of sulfur and 2 parts of TMTD accelerator, make a triangle roll 3 times, and then thinly pass 3 times to evenly disperse the material and then sheet it to obtain a damping rubber composition for rail fasteners.

[0054] Example 4

[0055] S1. 70# asphalt and GMA modified vinyl elastomer SOG-03 are mixed uniformly at a mass ratio of 10:5, added to a parallel co-rotating twin-screw extruder for hot melting to form a viscoelastic body, and the extrusion temperature of each zone of the screw is controlled as follows: 90°C in zone 1; 100°C in zone 2; 120°C in zone 3; 140°C in zone 4; 150°C in zone 5; 130°C in zone 6; 120°C in zone 7; 120°C in zone 8; 110°C in zone 9; 110°C in zone 10; a feeding port is set in the fifth section of the parallel co-rotating twin-screw extruder, and the viscoelastic body and the silica aerogel are compounded in a volume ratio of 2:4, and the silica aerogel is continuously added according to the volume measurement by a weight loss scale, and the completely hot-melted asphalt and the GMA modified vinyl elastomer SOG-03 are adsorbed by the micropores of the silica aerogel, and extruded into sheets through a die to obtain damping particles;

[0056] S2. Prepare composite rubber with EPDM rubber, natural rubber and nitrile rubber in a mass ratio of 10:5:2. Take 100 parts of composite rubber, 5 parts of aromatic oil plasticizer and 10 parts of coumarone resin tackifier and add them into an internal mixer for mixing for 5 minutes. Then add 35 parts of damping particles, 20 parts of mica powder, 5 parts of glass fiber (diameter 10μm, length 5mm), 3 parts of magnesium oxide activator, antioxidants (anti-aging agent RD, antioxidant NBC, antioxidant DNP) The rubber compound is compounded in a mass ratio of 10:5:3) and 1-3 parts thereof are continuously mixed for 5 minutes, and the temperature of the rotor of the internal mixer is controlled to be lower than 120°C; the rubber compound is put into an open mixer, and the roller temperature of the open mixer is controlled to be 50-60°C by circulating cooling water in the roller. When the rubber compound forms a continuous roll, 3.0% sulfur, 1 part of CZ accelerator and 1 part of TMTD accelerator are added, and the rubber compound is triangularly packaged 5 times, and then thinly passed 3 times to evenly disperse the material before being unrolled to obtain a damping rubber composition for rail fasteners.

[0057] Comparative Example 1

[0058] During the implementation of Example 1, the damping particles were removed, and the performance change of the damping rubber after the damping particles were removed was analyzed.

[0059] Comparative Example 2

[0060] In the implementation process of Example 1, the prefabricated damping particles are eliminated, and instead 70# asphalt, SOG-03, and silica aerogel are directly added in equal amounts in step S2.

[0061] Comparative Example 3

[0062] During the implementation of Example 1, the fibers were removed, and the performance changes of the damping rubber after the fibers were removed were analyzed.

[0063] Comparative Example 4

[0064] During the implementation of Example 1, calcium carbonate was used to replace mica, and the performance changes of the damping rubber were analyzed.

[0065] Comparative Example 5

[0066] In the implementation process of Example 1, the GMA-modified vinyl elastomer is eliminated when prefabricating damping particles in step S1, and the performance change of the damping rubber is analyzed.

[0067] Performance evaluation and analysis test:

[0068] The damping rubber compositions of Examples 1-4 and Comparative Examples 1-5 were added to a pin-type cold feed extruder, and the screw temperatures were controlled as follows: Zone 1 temperature 65°C, Zone 2 temperature 60°C, Zone 3 temperature 55°C, and die head temperature 70°C; the sheets were extruded at the die mouth through shearing and kneading, placed on a louver for 24 hours, cut and placed in a mold, and vulcanized for 15 minutes at a pressure of 15MPa and a temperature of 170°C to obtain a test sample. The comprehensive performance of the material was evaluated by testing the basic mechanical properties, hardness, aging resistance, load impact fatigue resistance, damping performance, etc. of the test samples:

[0069] 1. Shore hardness test

[0070] Referring to the standard GB / T 531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber Part 1: Shore hardness method (Shore hardness)", the Shore A hardness of the test sample was tested. The test results are shown in Table 1.

[0071] (II) Basic mechanical properties test

[0072] Referring to the standard GB / T528 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", after punching the specimens, the tensile strength, elongation at break and 200% modulus of elongation were tested at room temperature at a tensile rate of 500 mm / min. The test results are shown in Table 1.

[0073] (III) Aging resistance test

[0074] According to the standard GB / T 3512 "Hot air accelerated aging and heat resistance test for vulcanized rubber or thermoplastic rubber", the hardness and mechanical properties of the test samples were tested after aging at 100°C for 72 hours under air supply conditions. The test results are shown in Table 1.

[0075] Table 1 Mechanical properties and aging resistance of samples

[0076]

[0077] (IV) Damping performance test

[0078] When vulcanized rubber samples are subjected to alternating stress, the strain lags behind the stress due to the movement of the molecular chain. This hysteresis phenomenon gives the material mechanical energy loss, thus having damping properties. The tangent value tanδ of the phase angle δ between the strain lag and the stress is used as the damping factor to characterize the damping performance.

[0079] Referring to the standard GB / T 9870 "Determination of dynamic properties of vulcanized rubber or thermoplastic rubber Part 2: Low-frequency torsion pendulum method" and the forced vibration method, the loss modulus E" and storage modulus E' of the samples were tested at -50℃, -30℃-10℃, 10℃, 30℃, and 50℃ using a dynamic mechanical analyzer at a frequency of 100Hz. The damping factor tanδ value is obtained by the ratio of the loss modulus E" to the storage modulus E'. The test results are shown in Table 2.

[0080] Table 2 Damping performance of samples

[0081]

[0082] (V) High load impact fatigue test

[0083] Referring to the experimental method in Appendix C of GB-T21527 "Elastic Pads for Rail Transit Fastener Systems", a load of 150kN was generated at a frequency of 4Hz, and 3 million load cycles were applied to the sample to measure the permanent deformation and static stiffness change of the sample to measure the ability to resist load impact. Permanent deformation less than 10% and static stiffness change less than 15% are considered qualified. The test results are shown in Table 3.

[0084] Table 3 Load impact fatigue resistance of samples

[0085]

[0086] The above test data show that the damping rubber of the present invention has excellent mechanical properties and heat-resistant oxidation properties; it has significant viscoelastic characteristics, so that its strain lags significantly behind the stress and has good damping performance. Figure 1 The figure shows the relationship between the damping factor and temperature tanδ-T of Examples 1-4. The damping factor tanδ reaches a peak value at about 10°C and is stable. In the temperature range of -50°C to 50°C, the damping factor tanδ is ≥ 0.3. The effective damping temperature range is wide and the adaptability to working conditions is strong. Especially under load impact, the sample has small permanent deformation and low static stiffness change rate, and has excellent performance in long-term resistance to impact deformation and fatigue.

[0087] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A damping rubber for rail fasteners, characterized in that: The invention comprises the following raw materials measured by weight: 100 parts of composite rubber, 25-35 parts of damping particles, 15-20 parts of sheet structure filler, 5-10 parts of plasticizer, 5-10 parts of tackifier, 3-5 parts of high temperature resistant fiber, 2-4 parts of vulcanizer, 3-5 parts of activator, 2-2.5 parts of accelerator and 1-3 parts of antioxidant; wherein: The composite rubber is a composite of EPDM rubber, natural rubber and nitrile rubber; The damping particles are elastic particles obtained by filling aerogel nanopores with asphalt and glycidyl methacrylate modified elastomer.

2. The damping rubber for rail fasteners according to claim 1, characterized in that: The composite rubber is a composite of EPDM rubber, natural rubber and nitrile rubber in a mass ratio of 10:(3-8):(1-2).

3. The damping rubber for rail fasteners according to claim 1, characterized in that: The damping particles are elastic particles obtained by filling aerogel nanopores with a viscoelastic body formed by blending asphalt with a glycidyl methacrylate modified elastomer; wherein the aerogel is at least one of silica aerogel, alumina aerogel, and polyimide aerogel with a porosity greater than 75% and a pore size less than 100nm.

4. The damping rubber for rail fasteners according to claim 1, characterized in that: The damping particles are compounded by a viscoelastic body formed by blending asphalt with a glycidyl methacrylate modified elastomer and aerogel in a volume ratio of 2:(3-4).

5. The damping rubber for rail fasteners according to claim 4, characterized in that: The viscoelastic body is compounded by asphalt and glycidyl methacrylate modified elastomer in a mass ratio of 10:(2-5).

6. The damping rubber for rail fasteners according to claim 1, characterized in that: The glycidyl methacrylate modified elastomer is at least one of a GMA-modified thermoplastic polyester elastomer, a GMA-modified thermoplastic polyurethane elastomer, a GMA-modified styrene-butadiene-styrene triblock copolymer, a GMA-modified ethylene acrylic acid copolymer, and a GMA-modified ethylene-vinyl acetate copolymer.

7. The damping rubber for rail fasteners according to claim 1, characterized in that: The sheet structure filler is at least one of mica powder, kaolin, montmorillonite and pyrophyllite.

8. The damping rubber for rail fasteners according to claim 1, characterized in that: The plasticizer is at least one of pine tar, dioctyl phthalate, and aromatic oil; the tackifier is at least one of coumarone resin, rosin resin, alkyl phenolic resin, petroleum resin, and terpene resin; the vulcanizer is sulfur; the activator is at least one of zinc oxide, stearic acid, zinc carbonate, and magnesium oxide; the accelerator is at least one of CZ, TBBS, NOBS, DZ, TMTD, TMTM, TETD, DPTT, ZDC, BZ, and PZ; the antioxidant is antioxidant RD, antioxidant NBC, and antioxidant DNP, which are prepared in a mass ratio of 10:(3-5):(2-3).

9. The damping rubber for rail fasteners according to claim 1, characterized in that: The high temperature resistant fiber is at least one of ceramic fiber, glass fiber, polyphenylene sulfide fiber and polytetrafluoroethylene fiber with a diameter of 10-20 μm and a length of 3-6 mm.

10. A method for preparing a damping rubber for rail fasteners according to any one of claims 1 to 9, characterized in that: The specific preparation method is as follows: S1. The asphalt and the glycidyl methacrylate modified elastomer are mixed evenly, added to the co-rotating twin-screw extruder for hot melt extrusion; a feeding port is set in the fifth section of the co-rotating twin-screw extruder, and aerogel is continuously added according to volume measurement by a loss-in-weight scale, and the aerogel micropores adsorb the completely hot-melt asphalt and glycidyl methacrylate modified elastomer, and extruded into sheets through a die to obtain damping particles; S2. Add 100 parts of composite rubber, 5-10 parts of plasticizer and 5-10 parts of tackifier into an internal mixer and mix for 3-5 minutes, then add 25-35 parts of damping particles, 10-15 parts of sheet structure filler, 3-5 parts of high temperature resistant fiber, 3-5 parts of activator and 1-3 parts of antioxidant and continue mixing for 5-8 minutes, and control the rotor temperature of the internal mixer to be lower than 120°C; put the rubber material into an open mixer, and control the roller temperature of the open mixer to 50-60°C with circulating cooling water in the roller. When the rubber material forms a continuous roll, add 2-4 parts of vulcanizer and 2-2.5 parts of accelerator, make a triangle package 3-5 times, and then thinly pass 3 times to evenly disperse the material before unrolling to obtain a damping rubber composition for rail fasteners.

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