Polyol-based heavy haul railway pad and method of making and use thereof

Abstract

The present disclosure relates to the technical field of polyurethane materials, and provides a polyol and a preparation method and application thereof. The raw materials of the polyol include, in parts by weight, 20-80 parts of a methacrylate monomer, 20-80 parts of a vinyl acetate, 1-20 parts of a hydroxyl monomer, 0-20 parts of a modified monomer, 10-100 parts of an active diluent, 0.1-5 parts of an initiator, and 0-3 parts of a molecular weight regulator; the hydroxyl monomer includes at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, and N-hydroxymethyl acrylamide; and the modified monomer includes at least one of acrylamide, N-hydroxymethyl acrylamide, maleic anhydride, and itaconic acid. The present disclosure also provides a heavy-haul railway pad and a preparation method and application thereof. The heavy-haul railway pad is prepared by using the above-mentioned polyol designed and synthesized by the present disclosure, and at least has the effect of making the heavy-haul railway pad have excellent rigidity and toughness, high-temperature and low-temperature resistance, and buffering and assembly fatigue performance.

Description

Technical Field

[0001] This disclosure relates to the field of polyurethane materials technology, for example to a heavy-duty railway pad based on polyols, its preparation method, and its application. Background Technology

[0002] Heavy-haul railways are one of the main arteries of modern national economies. Developing heavy-haul railway transportation is a major international trend in freight rail transport and an effective way to expand the capacity and efficiency of existing railways. Heavy-haul railways have significant advantages such as large capacity, low cost, good economy, and high transport efficiency. In China, heavy-haul railways mostly operate on a conventional axle load-heavy, high-capacity heavy-haul transport model. With the continuous improvement of my country's high-speed railway network, the basic conditions for passenger and freight separation have been created. Freight transport is developing towards speed, large capacity, and large axle load. On the one hand, research is being conducted on developing heavy-haul transport with axle loads of 30 tons and above; on the other hand, in-depth research is being conducted on scientific maintenance methods for existing railways and heavy-haul corridors to rationally improve the potential of heavy-haul transport, further optimize my country's railway network capacity, reduce line maintenance costs, and maximize economic benefits.

[0003] To achieve the healthy development of heavy-haul rail transit in my country, it is of great practical significance to conduct extensive and in-depth research on the service performance and degradation patterns of equipment, considering the characteristics of heavy-haul transportation modes, and to continuously improve the performance and working condition of related components to extend equipment lifespan. Among these efforts, mitigating the dynamic impact of wheel-rail dynamics through the rational setting of track elasticity and the development and application of high-performance elastic components has always been a goal pursued by railway engineering technicians.

[0004] Currently, the challenges facing the operation and maintenance of heavy-haul railway lines in my country include: continuously improving heavy-haul railway transportation standards, necessitating strengthened technical standards for line structures; further improvement in the technical performance of key components; poor track structure elasticity, deteriorating line service performance; and a prominent contradiction between long tunnel defects and high transport capacity. Based on these factors, maintaining track geometry is difficult, ballast bed compaction is severe, and track bed cleaning and maintenance are challenging due to time and space constraints and limited maintenance resources. The elasticity of the track structure largely relies on the under-rail pads.

[0005] my country's heavy-haul railways currently mainly use ordinary rubber elastic pads and thermoplastic polyester elastomer (TPEE) pads. Among them, the former is prone to damage and loss of elasticity due to insufficient strength and difficulty in guaranteeing the quality of supply. The latter has a measured stiffness of up to 250kN / mm and exhibits significant glassization under low temperature conditions, further increasing its stiffness. This leads to a decrease in the ability of the almost inelastic rail pad to reduce wheel-rail dynamic impact and distribute wheel load, resulting in an increase in the train load on a single sleeper, increased contact stress on components, and a series of problems such as "gnawing" at the rail bearing groove.

[0006] Polyurethane materials possess high molecular structure designability, and theoretically, heavy-duty railway pads meeting various performance requirements can be prepared through reasonable molecular structure design. However, current research and development on polyurethane gaskets for heavy-duty railway pads reported in the literature are all based on existing commercially available polyols. Their performance and raw material costs are severely constrained by the availability of commercially available polyols, making it difficult to simultaneously meet the requirements for high elasticity, high rigidity, and long-term use (aging) performance of polyurethane gaskets. Furthermore, the high cost makes it difficult to promote polyurethane gaskets based on commercially available polyols in the market. Summary of the Invention

[0007] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a polyol, its preparation method and application, and a heavy-duty railway pad, its preparation method and application. The polyol was designed and synthesized in-house, and the heavy-duty railway pad was prepared using the polyol, so as to at least achieve the effect of making the heavy-duty railway pad have excellent rigidity and toughness, high temperature and low temperature resistance, and cushioning and assembly fatigue performance.

[0008] The purpose of this disclosure is achieved through the following technical solution:

[0009] On one hand, a polyol is provided. By weight, the raw materials of the polyol include 20-80 parts of methacrylate monomer, 20-80 parts of vinyl acetate, 1-20 parts of hydroxyl monomer, 0-20 parts of modified monomer, 10-100 parts of reactive diluent, 0.1-5 parts of initiator, and 0-3 parts of molecular weight regulator; wherein the hydroxyl monomer includes at least one selected from hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, and N-hydroxymethylacrylamide; and the modified monomer includes at least one selected from acrylamide, N-hydroxymethylacrylamide, maleic anhydride, and itaconic acid.

[0010] It should be noted that the phrase "the raw material of the polyol includes 0 to 20 parts of the modified monomer" in the above text means that the raw material of the polyol may or may not include the modified monomer (i.e., the raw material of the polyol includes 0 parts of the modified monomer). In some examples, the raw material of the polyol does not include the modified monomer (i.e., the raw material of the polyol includes 0 parts of the modified monomer).

[0011] Similarly, the phrase "the raw materials of the polyol include 0 to 3 parts of the molecular weight regulator" in the above text means that the raw materials of the polyol may or may not include the molecular weight regulator (i.e., the raw materials of the polyol include 0 parts of the molecular weight regulator). In some examples, the raw materials of the polyol include the molecular weight regulator.

[0012] In some embodiments, the methacrylate monomer includes at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, isooctyl methacrylate, isobornyl methacrylate, dodecyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0013] In some embodiments, the reactive diluent includes at least one of ethylene glycol, propylene glycol, butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, dipropylene glycol, polypropylene glycol, polypropylene glycol, polyethylene glycol, and polybutylene glycol.

[0014] In some embodiments, the initiator includes at least one of peroxide and azo compound.

[0015] In some examples, the peroxide includes benzoyl peroxide.

[0016] In some examples, the azo compound includes azobisisobutyronitrile (AIBN).

[0017] In some embodiments, the molecular weight regulator includes a thiol compound.

[0018] In some embodiments, the thiol compound includes dodecyl thiol.

[0019] It is worth noting that the advantages of the polyols provided in this disclosure include at least the following: adjustable molecular weight; a wide range of soft and hard monomers to choose from and adjustable in proportion, which can simultaneously take into account the rigidity and toughness of heavy-duty railway pads as well as high-temperature and low-temperature resistance; and low cost of raw materials, with a significant price advantage.

[0020] On the other hand, a method for preparing polyols as described in any of the above embodiments is provided. The method includes: uniformly mixing the methacrylate monomer, the vinyl acetate, the hydroxyl monomer, the modified monomer, and the molecular weight regulator to obtain a polymerizable monomer; dissolving a portion of the reactive diluent in combination with the initiator to obtain an initiator solution; adding the remaining portion of the reactive diluent, a portion of the initiator solution, and a portion of the polymerizable monomer into a reaction vessel and starting stirring; heating the reaction vessel to 50–100°C and reacting for 20–60 minutes to obtain a first reaction solution; and separately dissolving the remaining portion of the initiator solution... A portion of the initiator solution and the remaining portion of the polymerizable monomer are simultaneously added dropwise to the first reaction solution to obtain a second reaction solution; wherein, the time for adding the remaining portion of the initiator solution is the first adding time, and the time for adding the remaining portion of the polymerizable monomer is the second adding time, the first adding time being 1-8 hours, the second adding time being 1-8 hours, and the difference between the first adding time and the second adding time not exceeding 2 hours; and the second reaction solution is kept at a constant temperature for 3-4 hours, and the reaction vessel is cooled to below 50°C to obtain the polyol.

[0021] In some embodiments, a portion of the reactive diluent accounts for 10% to 25% of the total weight of the reactive diluent.

[0022] In some embodiments, a portion of the initiator solvent accounts for 10% to 50% of the total weight of the initiator solvent.

[0023] In some embodiments, a portion of the polymeric monomer accounts for 5% to 30% of the total weight of the polymeric monomer.

[0024] In another aspect, the application of the polyol as described in any of the above embodiments or the method described in any of the above embodiments in the preparation of heavy-duty railway pads is provided.

[0025] On another front, a heavy-duty railway pad is provided. The raw materials of the heavy-duty railway pad include a first component and a second component; wherein, by weight, the first component includes 100 parts of polyol as described in any of the above embodiments, 0-5 parts of catalyst, 0.1-10 parts of water, 0.1-0.5 parts of foaming agent, and 0-100 parts of filler; by weight, the second component includes 100 parts of aromatic isocyanate and 0-50 parts of viscosity modifier; the mass ratio of the first component to the second component is 100:5-100.

[0026] It should be noted that "the first component includes 0 to 5 parts of the catalyst" in the above text means that the first component may or may not include the catalyst (i.e., the first component includes 0 parts of the catalyst). In some examples, the first component includes the catalyst.

[0027] Similarly, the phrase "the first component includes 0 to 100 parts of the filler" above means that the first component may or may not include the filler (i.e., the first component includes 0 parts of the filler). In some examples, the first component does not include the filler.

[0028] Similarly, the phrase "the second component includes 0 to 50 parts of the viscosity modifier" in the above text means that the second component may or may not include the viscosity modifier (i.e., the second component includes 0 parts of the viscosity modifier).

[0029] In some embodiments, the catalyst includes at least one of amine catalysts and metal catalysts.

[0030] In some examples, the amine catalyst includes at least one of triethyl-phenylene diamine, methyl di-ethyl-phenylene diamine, methyl di-ethyl-phenylene diamine, methyl di-ethyl-phenylene diamine, and catalyst 33LV, such as triethyl-phenylene diamine.

[0031] In some examples, the metal catalyst includes at least one of organotin salts, organobismuth salts, and organozinc salts. Exemplarily, the metal catalyst is an organotin salt, such as dibutyltin dilaurate or dibutyltin.

[0032] In some embodiments, the foaming agent comprises an organopolysiloxane.

[0033] In some examples, the organopolysiloxane includes siloxane-oxoalkylene copolymers.

[0034] In some embodiments, the filler includes at least one of color powder, calcium carbonate, talc, titanium dioxide, aluminum hydroxide, magnesium hydroxide, ceramic powder, glass powder, and quartz powder.

[0035] In some embodiments, the aromatic isocyanate includes at least one of TDI or its polymer, MDI or its polymer, and NDI or its polymer.

[0036] In some examples, the aromatic isocyanate includes MDI, such as industrial grade MDI50.

[0037] In other examples, the aromatic isocyanate includes MDI polymers, such as PM200 or PM400.

[0038] In some embodiments, the viscosity modifier includes at least one of a plasticizer, a softener, and a solvent.

[0039] In some examples, the viscosity modifier includes a plasticizer, such as dibutyl phthalate or dioctyl phthalate.

[0040] In another aspect, a method for preparing a heavy-duty railway pad as described in any of the above embodiments is provided. The method includes: uniformly mixing the polyol, the catalyst, the foaming agent, the water, and the filler to obtain a first component; uniformly mixing the aromatic isocyanate and the viscosity modifier to obtain a second component; preheating the first component and the second component to 40–60°C respectively, then mixing them, pouring the mixture into a mold with a mold temperature of 0–80°C, waiting 2–30 minutes before demolding, and subjecting it to a first curing process to obtain a preliminary product; and subjecting the preliminary product to a second curing process to obtain the heavy-duty railway pad.

[0041] In the method for preparing the heavy-haul railway pad provided in this disclosure, the second component contains abundant isocyanate groups (-NCO), which can react with the hydroxyl groups (-OH) of the polyol in the first component to generate urethane groups, thereby extending the chain or crosslinking; on this basis, the isocyanate groups in the second component can also react with the water in the first component to generate urea bonds, thereby extending the chain and generating carbon dioxide for foaming, thereby preparing the heavy-haul railway pad.

[0042] Based on this, it is easy to understand that when the reaction temperature is increased or the amount of catalyst is increased, the reaction rate of isocyanate groups with hydroxyl groups and water can be accelerated, thereby shortening the reaction time; when the isocyanate groups in the reaction system are exhausted, the reaction terminates.

[0043] In some embodiments, the first maturation includes a first room temperature maturation; wherein the first room temperature maturation time is 12 to 48 hours.

[0044] In some embodiments, the second curing includes at least one of high-temperature curing and second room-temperature curing; wherein the high-temperature curing temperature is 60-150°C and the high-temperature curing time is 0.3-24h; and the second room-temperature curing time is 4-240h.

[0045] In another aspect, an application is provided for the heavy-duty railway pad as described in any of the above embodiments or the method described in any of the above embodiments in the preparation of a railway fastening system.

[0046] It should be noted that when the heavy-duty railway pad is applied to the railway fastening system, it is installed between the rail and the concrete sleeper to provide shock absorption and cushioning.

[0047] In summary, based on the performance requirements of heavy-haul railway pads, this disclosure innovatively designs and synthesizes a polyol with methacrylate and vinyl acetate as the main monomers. Furthermore, using the polyol, catalyst, foam stabilizer, water, filler, aromatic isocyanate, and viscosity modifier as raw materials, the combined effect of these raw materials on material properties ultimately yields a heavy-haul railway pad with high strength, high toughness, low creep, and weather resistance. Notably, the polyol with methacrylate and vinyl acetate as the main monomers in this disclosure is an amorphous polyol. By controlling the selection and ratio of soft and hard monomers, the glass transition temperature of the polyol can be adjusted, resulting in a substantially amorphous region in the soft segments of the resulting polyurethane pad (i.e., the heavy-haul railway pad).

[0048] Furthermore, this disclosure utilizes molecular microscopic theory to introduce hard small molecular chain segments with polar bond energies onto flexible macromolecular monomers for crosslinking. Through modification of the molecular chains and appropriate crosslinking at high temperatures, the main chain exhibits good flexibility due to the influence of the flexible segments, while the rigid segments crosslink between the macromolecular chains, forming a three-dimensional network structure where flexible and hard molecular chains intersect. Simultaneously, the high chemical bond energy between molecules enables the heavy-duty railway pad to possess high mechanical properties. In addition, the appropriate degree of crosslinking structure also enables the heavy-duty railway pad to have strong compressive strength and good resilience.

[0049] The beneficial effects of this disclosure are:

[0050] 1. The present disclosure provides a polyol with superior performance and lower cost than existing commercial polyols.

[0051] 2. The heavy-duty railway pad provided in this disclosure has excellent balance between rigidity and toughness, and causes little wear on the sleepers.

[0052] 3. The heavy-haul railway pad provided in this disclosure has better fatigue performance. After long-term use, the static stiffness changes little and the rate of change is stable, which can maintain the stiffness stability of heavy-haul railways for a long time.

[0053] 4. The heavy-haul railway pad provided in this disclosure has the advantages of aging resistance, long service life, and can reduce the maintenance cost of heavy-haul railways.

[0054] 5. The method for preparing heavy-duty railway pads provided in this disclosure has the advantages of simple, mild and easy-to-control process, without the need for complex processes, and has obvious advantages in efficiency and cost. Detailed Implementation

[0055] The technical solutions in some embodiments of this disclosure will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments provided in this disclosure, all other embodiments obtained by those skilled in the art are within the scope of protection of this disclosure.

[0056] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0057] "At least one of A, B, and C" has the same meaning as "at least one of A, B, or C", both including the following combinations of A, B, and C: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B, and C. "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0058] In describing some embodiments, the expression "A and / or B" may be used. It is readily understood that "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0059] As used herein, “approximately” includes the values ​​stated and the average value within an acceptable range of deviation from the given values, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the given quantity (i.e., the limitations of the measurement system).

[0060] The term "room temperature" or "room temperature" typically refers to approximately 25°C. In some embodiments of this disclosure, the temperature range for "room temperature" or "room temperature" may be 20–25°C.

[0061] Example 1

[0062] 1. A polyol, the raw materials of which include 20 kg of methyl methacrylate, 80 kg of vinyl acetate, 5 kg of hydroxyethyl acrylate, 40 kg of polypropylene glycol (PPG, average molecular weight 425), 0.5 kg of benzoyl peroxide, and 0.01 kg of dodecyl mercaptan.

[0063] 2. The method for preparing the above polyols includes S1 to S5.

[0064] S1. Mix 20 kg of methyl methacrylate, 80 kg of vinyl acetate, 5 kg of hydroxyethyl acrylate and 0.01 kg of dodecyl mercaptan to obtain the polymer monomer.

[0065] S2. Mix and dissolve 5.5 kg of polypropylene glycol and 0.5 kg of benzoyl peroxide to obtain an initiator solution.

[0066] S3. Add the remaining 34.5 kg of polypropylene glycol, 2 kg of initiator solution and 30 kg of monomer to the reactor and turn on the stirrer and heat exchanger. Heat the reactor to 80°C and react for 40 min to obtain the first reaction solution.

[0067] S4. The remaining 4 kg of initiator solution and the remaining 75.01 kg of polymer monomer are respectively placed into two drop-addition tanks and simultaneously added to the first reaction solution to obtain the second reaction solution; wherein, the time for adding the remaining initiator solution is 250 min and the time for adding the remaining polymer monomer is 240 min, and the error in the time of addition does not exceed 5 min.

[0068] S5. The second reaction solution is kept at a constant temperature for 4 hours. The reaction vessel is then cooled to below 50°C. After metering and packaging, the polyol is obtained.

[0069] 3. A heavy-duty railway pad, the raw materials of which include a first component and a second component; wherein, the first component includes 100 kg of the above-mentioned polyol, 0.1 kg of dibutyltin dilaurate, 6.5 kg of water and 0.2 kg of siloxane-oxoalkylene copolymer; the second component includes 100 kg of MDI polymer PM200 and 10 kg of dioctyl phthalate.

[0070] 4. The method for preparing the above-mentioned heavy-haul railway pad includes steps S100 to S400.

[0071] S100. Place 100 kg of the above polyol, 0.1 kg of dibutyltin dilaurate, 6.5 kg of water and 0.2 kg of siloxane-oxoalkylene copolymer into a mixing container, and stir thoroughly at room temperature for 30 min to mix evenly to obtain the first component.

[0072] S200. Place 100 kg of MDI polymer PM200 and 10 kg of dioctyl phthalate into a mixing container and stir thoroughly at room temperature for 30 min to obtain the second component.

[0073] S300. Preheat the first component to 45°C and the second component to 43°C. Mix the two components at a mass ratio of 80:30 and pour the mixture into a mold at a temperature of 65°C. After waiting for 15 minutes, demold the mixture and allow it to mature at room temperature for 24 hours to obtain the initial product.

[0074] S400. Place the initial product in an oven at 100℃ for 8 hours to mature, and then leave it at room temperature for 7 days to mature, thus obtaining the heavy-duty railway pad.

[0075] Example 2

[0076] 1. A polyol, the raw materials of which include 45 kg of methyl methacrylate, 55 kg of vinyl acetate, 8 kg of hydroxyethyl acrylate, 50 kg of polybutanediol (PTMG, average molecular weight 250), 0.6 kg of azobisisobutyronitrile, and 0.01 kg of dodecyl mercaptan.

[0077] 2. The method for preparing the above polyols includes S1 to S5.

[0078] S1. Mix 45 kg of methyl methacrylate, 55 kg of vinyl acetate, 8 kg of hydroxyethyl acrylate and 0.01 kg of dodecyl mercaptan to obtain the polymer monomer.

[0079] S2. Mix and dissolve 5.4 kg of polybutanediol and 0.6 kg of azobisisobutyronitrile to obtain an initiator solution.

[0080] S3. Add the remaining 44.6 kg of polybutanediol, 2 kg of initiator solution and 25 kg of monomer to the reactor and turn on the stirrer and heat exchanger. Heat the reactor to 75°C and react for 40 min to obtain the first reaction solution.

[0081] S4. The remaining 4 kg of initiator solution and the remaining 83.01 kg of polymer monomer are respectively placed into two drop-addition tanks and simultaneously added to the first reaction solution to obtain the second reaction solution; wherein, the time for adding the remaining initiator solution is 250 min and the time for adding the remaining polymer monomer is 240 min, and the error in the time of addition does not exceed 5 min.

[0082] S5. The second reaction solution is kept at a constant temperature for 3 hours. The reaction vessel is then cooled to below 50°C. After metering and packaging, the polyol is obtained.

[0083] 3. A heavy-duty railway pad, the raw materials of which include a first component and a second component; wherein, the first component includes 100 kg of the above-mentioned polyol, 0.1 kg of triethyl-phenylene diamine, 5.0 kg of water and 0.2 kg of siloxane-oxoalkylene copolymer; the second component is 100 kg of industrial grade MDI50.

[0084] 4. The method for preparing the above-mentioned heavy-haul railway pad includes steps S100 to S300.

[0085] S100. Place 100 kg of the above polyol, 0.1 kg of triethyl-phenylene diamine, 5.0 kg of water and 0.2 kg of siloxane-oxoalkylene copolymer into a mixing container, and stir thoroughly at room temperature for 30 min to mix evenly to obtain the first component.

[0086] S200. Preheat the first component to 40°C and the second component to 40°C. Mix the two components at a mass ratio of 80:30 and pour the mixture into a mold with a mold temperature of 60°C. After waiting for 10 minutes, demold the mixture and let it mature at room temperature for 24 hours to obtain the initial product.

[0087] S300. Place the initial product in an oven at 100℃ for 12 hours to mature, and then leave it at room temperature for 7 days to mature, thus obtaining the heavy-duty railway pad.

[0088] Example 3

[0089] 1. A polyol, the raw materials of which include 80 kg of methyl methacrylate, 20 kg of vinyl acetate, 6 kg of hydroxyethyl acrylate, 30 kg of polypropylene glycol (PPG 330N, hydroxyl value 35), 10 kg of ethylene glycol, 0.5 kg of azobisisobutyronitrile and 0.01 kg of dodecyl mercaptan.

[0090] 2. The method for preparing the above polyols includes S1 to S5.

[0091] S1. Mix 80 kg of methyl methacrylate, 20 kg of vinyl acetate, 6 kg of hydroxyethyl acrylate and 0.01 kg of dodecyl mercaptan to obtain the polymer monomer.

[0092] S2. Mix and dissolve 10 kg of ethylene glycol with 0.5 kg of azobisisobutyronitrile to obtain an initiator solution.

[0093] S3. Add 30 kg of polypropylene glycol, 3.5 kg of initiator solution and 25 kg of monomer to the reactor and turn on the stirrer and heat exchanger. Heat the reactor to 78°C and react for 40 min to obtain the first reaction solution.

[0094] S4. The remaining 7 kg of initiator solution and the remaining 81.01 kg of polymer monomer are respectively loaded into two drop-addition tanks and simultaneously added to the first reaction solution to obtain the second reaction solution; wherein, the time for adding the remaining initiator solution is 220 min and the time for adding the remaining polymer monomer is 210 min, and the error in the time of addition does not exceed 5 min.

[0095] S5. The second reaction solution is kept at a constant temperature for 3 hours. The reaction vessel is then cooled to below 50°C. After metering and packaging, the polyol is obtained.

[0096] 3. A heavy-duty railway pad, the raw materials of which include a first component and a second component; wherein, the first component includes 100 kg of the above-mentioned polyol, 0.1 kg of dibutyltin, 3.5 kg of water and 0.1 kg of siloxane-oxoalkylene copolymer; the second component includes 100 kg of MDI polymer PM400 and 20 kg of dibutyl phthalate.

[0097] 4. The method for preparing the above-mentioned heavy-haul railway pad includes steps S100 to S400.

[0098] S100. Place 100 kg of the above polyol, 0.1 kg of dibutyltin, 3.5 kg of water and 0.1 kg of siloxane-oxoalkylene copolymer into a mixing container, and stir thoroughly at room temperature for 30 min to mix evenly to obtain the first component.

[0099] S200. Place 100 kg of MDI polymer PM400 and 20 kg of dibutyl phthalate into a mixing container and stir thoroughly at room temperature for 30 min to obtain the second component.

[0100] S300. Preheat the first component to 40°C and the second component to 45°C. Mix the two components at a mass ratio of 60:50 and pour the mixture into a mold at a temperature of 65°C. After waiting for 15 minutes, demold the mixture and allow it to mature at room temperature for 24 hours to obtain the initial product.

[0101] S400. Place the initial product in a 90℃ oven for 8 hours and then let it mature at room temperature for 7 days to obtain a heavy-duty railway pad.

[0102] Test results

[0103] To verify the performance of the heavy-duty railway pads provided in this disclosure, the physical and mechanical properties of the heavy-duty railway pads in embodiments 1 to 3 of this disclosure were tested. The methods and results are shown in the table below:

[0104]

[0105] It can be seen from the above table:

[0106] 1) The heavy-haul railway pads of Examples 1 to 3 can achieve stiffness indicators suitable for heavy-haul railways under high strength.

[0107] 2) The heavy-duty railway pads in Examples 1 to 3 achieve smaller permanent compression deformation and increase elasticity, thus avoiding the risk of fasteners loosening during long-term use;

[0108] 3) The heavy-duty railway pads in Examples 1 to 3 have high elongation at break, which ensures their toughness and thus improves fatigue performance.

[0109] 4) The heavy-duty railway pads of Examples 1 to 3 also have excellent water resistance and oil resistance.

[0110] Therefore, the present disclosure provides a polyol, its preparation method and application, and a heavy-duty railway pad, its preparation method and application. The above-mentioned polyol was designed and synthesized, and the above-mentioned heavy-duty railway pad was prepared using the above-mentioned polyol. At least the above-mentioned heavy-duty railway pad has the effect of having excellent rigidity and toughness, high temperature resistance and low temperature resistance, as well as buffering and assembly fatigue performance.

[0111] The above description is merely a preferred embodiment of this disclosure. It should be understood that this disclosure is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this disclosure should be within the protection scope of the appended claims.

Claims

1. A heavy-duty railway pad, characterized in that, The raw materials for the heavy-duty railway pad include: The first component, by weight, comprises 100 parts polyol, 0-5 parts catalyst, 0.1-10 parts water, 0.1-0.5 parts foaming agent, and 0-100 parts filler; and The second component, by weight, includes 100 parts of aromatic isocyanate and 0-50 parts of viscosity modifier; The mass ratio of the first component to the second component is 100:5~100; The raw materials for the polyol, by weight, include: The mixture contains 20-80 parts of methacrylate monomer, 20-80 parts of vinyl acetate, 1-20 parts of hydroxyl monomer, 10-100 parts of reactive diluent, 0.1-5 parts of initiator, and 0-3 parts of molecular weight regulator. The hydroxy monomer includes at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, and N-hydroxymethylacrylamide; The methacrylate monomers include at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, isooctyl methacrylate, isobornyl methacrylate, dodecyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate. The active diluent includes at least one of ethylene glycol, propylene glycol, butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, dipropylene glycol, polypropylene glycol, polypropylene glycol, polyethylene glycol, and polybutylene glycol. The initiator includes at least one of peroxide and azo compound; The molecular weight regulator includes thiol compounds.

2. The heavy-duty railway pad according to claim 1, characterized in that, The catalyst includes at least one of amine catalysts and metal catalysts; And / or, the foaming agent comprises an organopolysiloxane; And / or, the filler includes at least one of color powder, calcium carbonate, talc, titanium dioxide, aluminum hydroxide, magnesium hydroxide, ceramic powder, glass powder, and quartz powder; And / or, the aromatic isocyanate includes at least one of TDI or its polymer, MDI or its polymer, and NDI or its polymer; And / or, the viscosity modifier includes at least one of a plasticizer, a softener, and a solvent.

3. The heavy-duty railway pad according to claim 1, characterized in that, The method for preparing the polyol includes: The methacrylate monomer, the vinyl acetate, the hydroxyl monomer, the modified monomer, and the molecular weight regulator are mixed evenly to obtain a polymerizable monomer; A portion of the active diluent is mixed and dissolved with the initiator to obtain an initiator solution; The remaining portion of the reactive diluent, a portion of the initiator solution, and a portion of the polymerizing monomer are added to the reactor and stirring is started. The reactor is heated to 50-100°C and reacted for 20-60 minutes to obtain the first reaction solution. The remaining portions of the initiator solution and the remaining portions of the polymerizable monomer are simultaneously added dropwise to the first reaction solution to obtain a second reaction solution; wherein the time for adding the remaining portion of the initiator solution is the first adding time, and the time for adding the remaining portion of the polymerizable monomer is the second adding time, the first adding time being 1-8 hours, the second adding time being 1-8 hours, and the difference between the first adding time and the second adding time not exceeding 2 hours; and The second reaction solution is kept at a constant temperature for 3-4 hours, and then the reaction vessel is cooled to below 50°C to obtain the polyol.

4. The heavy-duty railway pad according to claim 3, characterized in that, A portion of the reactive diluent accounts for 10% to 25% of the total weight of the reactive diluent; And / or, a portion of the initiator solvent accounts for 10% to 50% of the total weight of the initiator solvent; And / or, a portion of the polymeric monomer accounts for 5% to 30% of the total weight of the polymeric monomer.

5. A method for preparing the heavy-haul railway pad as described in claims 1-4, characterized in that, include: The polyol, the catalyst, the foaming agent, the water, and the filler are mixed evenly to obtain the first component; The aromatic isocyanate and the viscosity modifier are mixed evenly to obtain the second component; The first component and the second component are preheated to 40~60℃ respectively, then mixed and poured into a mold with a mold temperature of 0~80℃. After waiting for 2~30 minutes, the mixture is demolded and subjected to a first curing process to obtain the initial product. as well as The initial product is subjected to a second curing process to obtain the heavy-duty railway pad.

6. The method according to claim 5, characterized in that, The first maturation includes a first room temperature maturation; wherein the first room temperature maturation time is 12~48h; And / or, the second curing includes at least one of high-temperature curing and second room-temperature curing; wherein, the high-temperature curing temperature is 60~150℃, and the high-temperature curing time is 0.3~24h; the second room-temperature curing time is 4~240h.

7. The application of the heavy-duty railway pads as described in claims 1 to 4 or the method described in claims 5 to 6 in the preparation of railway fastening systems.

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