A high fatigue resistant polyurethane composition and a method of preparing a polyurethane foamed molded cured track bed and uses thereof

Abstract

The present application relates to a kind of high fatigue-resistant polyurethane composition and its preparation method and application, the polyurethane composition includes isocyanate component and isocyanate reactive component, the isocyanate reactive component includes polyether polyol 1, polyether polyol 2, polymer polyol, blowing agent, flame retardant, chain extender, crosslinking agent, surfactant, catalyst, pigment;The polyether polyol 1, polyether polyol 2 and polymer polyol are used together, and polyurethane raw material has low-temperature non-crystallization and fatigue resistance.The polyurethane composition of the present application meets the performance requirements of polyurethane foam for preformed curing bed and the requirements of preformed curing bed for fatigue resistance.

Description

Technical Field

[0001] This invention relates to the field of polyurethane materials, and particularly to a high fatigue-resistant polyurethane composition and a method for preparing and applying a polyurethane foam-molded and cured track bed. Background Technology

[0002] Track is one of the main technical equipment of railways and the foundation for train operation. Compared with ballastless track, ballasted track has advantages such as better elasticity and lower engineering investment. However, based on the current application status at home and abroad, as well as related research and experiments, ballasted track faces many challenges when designed and operated at speeds of 300 km / h and above, including ballast splashing, weak track bed stability, easy ballast pulverization, and rapid changes in track geometry. In recent years, in response to the needs of railway construction and operation in my country, domestic research has begun on polyurethane-cured track bed technology. The industry has developed a complete set of technologies with independent intellectual property rights, including high-speed railway polyurethane-cured track bed structure design, material preparation, construction technology and equipment, maintenance and repair.

[0003] Polyurethane-cured track bed is made by bonding ballast with polyurethane foam material, which has good elasticity and energy absorption properties. This track bed has the integrity and low maintenance of ballastless track bed, as well as the good elasticity and easy maintenance of ballasted track bed. It also has certain vibration reduction and noise reduction properties. In addition to high-speed and heavy-haul railways, it can also be used in urban rail transit such as subways and light rails.

[0004] With the rapid development of my country's transportation industry, large-scale railway construction is underway in high-altitude and frigid regions. These regions are characterized by large diurnal temperature variations, low minimum temperatures, and strong ultraviolet radiation, posing significant challenges to the construction of polyurethane-cured track beds.

[0005] Taking into account the construction process and performance requirements of cured track beds in high-altitude and cold regions, traditional polyurethane cured track bed materials must simultaneously meet the following characteristics: ① no crystallization at low temperatures; ② high physical and mechanical properties; ③ low water absorption; ④ high flame retardancy; ⑤ high aging resistance.

[0006] Patent CN202111529122.6 discloses a polyurethane composition, its preparation method and application, wherein the polyurethane reaction components are composed of a first polyether polyol, a second polyether polyol and a flame-retardant amine compound, and have the technical feature of being in a low-temperature (-20℃) liquid state. The comprehensive performance of the polyurethane foam meets the performance requirements of polyurethane foam for prefabricated curing track beds.

[0007] However, compared to the performance indicators of cured track bed precast components, polyurethane foam still lacks key properties such as the penetration and bonding of polyurethane components between the ballast and the fatigue resistance of the precast components. In particular, the precast components need to withstand repeated mechanical loads from passing trains during use, and fatigue resistance is a critical performance parameter determining whether the precast components can be safely and stably put into service. Therefore, China State Railway Group Co., Ltd. has emphasized the requirements for the fatigue resistance of precast components in its relevant technical requirements.

[0008] Against this backdrop, the shortcomings of the low-temperature non-crystallization target of polyurethane systems, as reported in patent CN202111529122.6, which relies solely on a low-temperature liquid polyether polyol scheme, become particularly apparent. It is generally accepted in the field of polymer materials that crystalline polymers, due to the presence of crystalline regions, limit the propagation of microcracks and therefore exhibit higher fatigue resistance than amorphous polymers with similar molecular structures. Because the polyurethane reactive component in this patented scheme is amorphous, its fatigue resistance is poor. Even if the resulting polyurethane foam meets the performance requirements, it is difficult to satisfy the technical requirements for fatigue resistance in the new standard.

[0009] Patents CN201410816023.X and CN201510556783.6 respectively reported methods for preparing polyurethane foam materials for railway ballast and cured track bed. They proposed the design of polyurethane composition systems in response to the relevant technical requirements of railway engineering. However, compared with the technical requirements of polyurethane cured track bed prefabrication in high-altitude and cold regions, especially the important indicator of fatigue resistance, there is a lack of targeted and effective solutions. At the same time, there is also a lack of testing on the fatigue resistance of the materials prepared by the proposed solutions.

[0010] Patent CN202110126614.4 addresses polyurethane foam for railway track bed curing and its preparation method under conditions of large temperature differences, rain, and ultraviolet radiation. While this solution meets technical specifications in terms of the overall performance of the final product, its preparation process requires heating the polyether polyol at 50–60°C for 6–12 hours to melt the crystalline raw material. In other words, this solution still uses a traditional polyurethane composition system for track bed curing, where polyether polyol crystallizes significantly at low temperatures. However, in actual production and construction, not only is heating and melting of the raw material necessary, but in the intermittent production process of prefabricated components, the complex piping of the equipment needs to be heated and cleaned after each batch. Otherwise, if the external temperature drops, the residual polyether polyol in the equipment piping will crystallize and clog the pipes. Therefore, even if the final product meets performance requirements, the processing cost and cycle time remain high when using traditional crystalline polyether polyols. Summary of the Invention

[0011] In response to the technical requirements of polyurethane curing track bed prefabrication in high-altitude and cold regions for the low-temperature non-crystallization, physical and mechanical properties, water absorption, flame retardancy, aging resistance, and especially fatigue resistance of polyurethane materials, and the serious deficiencies of existing technologies, this invention provides a polyurethane composition with high fatigue resistance.

[0012] Another object of the present invention is to provide a method for using the aforementioned high fatigue-resistant polyurethane composition to prepare a polyurethane foam-molded and cured track bed.

[0013] Another object of the present invention is to provide an application of this polyurethane foam-molded and cured track bed.

[0014] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0015] A high fatigue-resistant polyurethane composition is obtained by reacting an isocyanate component and an isocyanate reactive component, wherein the isocyanate reactive component comprises: polyether polyol 1, polyether polyol 2, polymer polyol, foaming agent, flame retardant, chain extender, crosslinking agent, surfactant, catalyst, and pigment; wherein

[0016] The polyether polyol 1 has an average functionality of 2 to 4.5, such as 2, 2.5, 3, 3.5, 4, 4.5, etc., preferably 2.5 to 3.5, and a hydroxyl value of 10 to 200 mgKOH / g, such as 10 mgKOH / g, 15 mgKOH / g, etc.

[0017] mgKOH / g, 20mgKOH / g, 25mgKOH / g, 30mgKOH / g, 35mgKOH / g, 40mgKOH / g, 50mgKOH / g, 60mgKOH / g, 70mgKOH / g, 80mgKOH / g, 90mgKOH / g, 100mgKOH / g, 130mgKOH / g, 150mgKOH / g, 180mgKOH / g, 200mgKOH / g, etc., preferably 20-40mgKOH / g, obtained by reacting ethylene oxide and propylene oxide, with an ethylene oxide content of 10-25wt%, such as 10wt%, 15wt%, 20wt%, 25wt%, etc., based on the total mass of propylene oxide and ethylene oxide being 100%;

[0018] The polyether polyol 2 has an average functionality of 1.5 to 3, such as 1.5, 2, 2.5, 3, etc., preferably 1.5 to 2.5, and a hydroxyl value of 10 to 200 mgKOH / g, such as 10 mgKOH / g, 15 mgKOH / g, 20 mgKOH / g, 25 mgKOH / g, 30 mgKOH / g, 35 mgKOH / g, 40 mgKOH / g, 50 mgKOH / g, 60 mgKOH / g, 70 mgKOH / g, 80 mgKOH / g, etc. The KOH / g, 90mgKOH / g, 100mgKOH / g, 130mgKOH / g, 150mgKOH / g, 180mgKOH / g, 200mgKOH / g, etc., preferably 20-40mgKOH / g, are obtained by reacting ethylene oxide and propylene oxide. The ethylene oxide content is 5-10wt%, such as 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, etc., based on the total mass of propylene oxide and ethylene oxide as 100%.

[0019] The polymer polyol, namely the graft copolymer polyether polyol, has an average functionality of 2 to 4.5, such as 2, 2.5, 3, 3.5, 4, 4.5, etc., preferably 3, and a hydroxyl value of 15 to 50 mgKOH / g, such as 15 mgKOH / g, 20 mgKOH / g, 25 mgKOH / g, 30 mgKOH / g, 35 mgKOH / g, 40 mgKOH / g, 45 mgKOH / g, 50 mgKOH / g, etc., preferably 20 to 40 mgKOH / g, and a solid content of 20 to 50 wt%, such as 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, etc., preferably 25 to 45 wt%.

[0020] Based on the total mass of the isocyanate reactive components, the amount of polyether polyol 1 (A) in the isocyanate reactive components is 30% to 50%, for example, 30%, 31%, 33%, 35%, 38%, 40%, 41%, 43%, 45%, 48%, 50%, etc.; the amount of polyether polyol 2 (B) is 20% to 45%, for example, 20%, 21%, 22%, 23%, 24%, 25%, 28%, 30%, 31%, 33%, 35%, 38%, 40%, 41%, 42%, 43%, 44%, 45%, etc.; and the amount of polymer polyol (C) is 9% to 10%, for example, 9%, 9.1%, 9.3%, 9.5%, 9.6%, 9.8%, 9.9%, 10%, etc.

[0021] In a preferred embodiment, the amounts of polyether polyol 1 (A), polyether polyol 2 (B), and polymer polyol (C) in the isocyanate reactive component simultaneously satisfy the following relationship:

[0022]

[0023] In some specific embodiments, the isocyanate component refers to a class of compounds having an isocyanate group, examples of which include, but are not limited to, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), naphthalene diisocyanate (DI), terephthalic diisocyanate (PPDI), 1,4-cyclohexane diisocyanate (CHDI), phenylenediamine diisocyanate (XDI), cyclohexane diisocyanate (XDI), trimethyl-1,6-hexamethylene diisocyanate (TMHDI), tetramethyl-m-phenylenediamine diisocyanate (TMXDI), norbornane diisocyanate (NBDI), dimethylbiphenyl diisocyanate (TODI), methylcyclohexyl diisocyanate (HTDI), etc., as well as prepolymers, modified products, polymers, etc. of such monomers. These isocyanate compounds can be used alone or in combination. Preferably, the isocyanate component NCO content is 12-25 wt%, such as 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, etc., and preferably 17 wt%.

[0024] In some specific embodiments, the polyether polyol 1 is a type of compound that is started by polyol and polymerized with epoxide. Examples of initiators include, but are not limited to, ethylene glycol, propylene glycol, 1,4-butanediol, dipropylene glycol, diethylene glycol, triethylene glycol, bisphenol A, glycerol, trimethylolpropane, diethanolamine, triethanolamine, ethylenediamine, toluenediamine, pentaerythritol, sorbitol, xylitol, sucrose, or mixtures thereof. The epoxide monomer can be block addition or random addition, preferably block addition, and more preferably average functionality 3. The polymerization is propylene oxide, and the end is ethylene oxide block addition.

[0025] In some specific embodiments, polyether polyol 2 is a class of compounds that are polymerized from polyols and epoxides. Examples of initiators include, but are not limited to, ethylene glycol, propylene glycol, 1,4-butanediol, dipropylene glycol, diethylene glycol, triethylene glycol, bisphenol A, glycerol, trimethylolpropane, diethanolamine, triethanolamine, ethylenediamine, toluenediamine, pentaerythritol, or mixtures thereof. The epoxide monomer can be block addition or random addition, preferably with an average functionality of 2 and random addition of the epoxide monomer.

[0026] In some specific embodiments, the polymer polyol refers to a type of graft copolymer polyol obtained by reacting polyether polyol and vinyl monomer. The polyether polyol can be polyethylene oxide polyol, polyethylene oxide polyol, polyethylene oxide-propylene oxide copolymer polyol, etc., which are commonly used in the art. The vinyl monomer can be acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl acrylate and alkyl acrylate, etc., preferably acrylonitrile and / or styrene.

[0027] In some specific implementations, the foaming agent may be selected from commonly used physical foaming agents and chemical foaming agents in the art, including but not limited to one or more of water, monochlorodifluoromethane, monochloromonofluoromethane, dichlorodifluoromethane, trichlorofluoromethane, butane, pentane, cyclopentane, hexane, cyclohexane, heptane, air, CO2 and N2, preferably water.

[0028] In some specific implementation schemes, the flame retardant may include, but is not limited to, halogenated phosphate flame retardants, phosphate flame retardants, halogenated hydrocarbons and other halogenated flame retardants, melamine and its salts, reactive flame retardants, inorganic flame retardants, etc., and these flame retardants may be used alone or in combination. Preferably, the flame retardant is selected from liquid flame retardants with a viscosity of 40-800 mPa·s at 25°C; more preferably, the flame retardant has a viscosity of 60-400 mPa·s at 25°C; even more preferably, the flame retardant is composed of flame retardant 1 and flame retardant 2, wherein flame retardant 1 refers to a flame retardant that can participate in the reaction, giving the polyurethane molecules obtained by the reaction flame-retardant function and having little impact on the material properties. Examples of flame retardant 1 include, but are not limited to, tris(dipropylene glycol) phosphite, diethyl N,N-di(2-hydroxyethyl)aminomethylenephosphonate, dimethyl N,N-di(2-hydroxyethyl)aminomethylphosphonate, FR212 (produced by Wanhua Chemical Company), etc. The flame retardant 2 refers to a class of flame retardants that can provide a flame retardant effect but do not participate in the reaction. Examples of flame retardant 2 include, but are not limited to, tris(2-chloroethyl) phosphate, (2-chloropropyl) phosphate, di(3-bromo-2,2-dimethylpropyl) phosphate, dimethyl methyl phosphate, diethyl ethyl phosphate, dimethyl propyl phosphate, triethyl phosphate, triphenyl phosphate, and tricresyl phosphate. The flame retardant of this invention enables the polyurethane composition to have good flame retardant effects while maintaining low viscosity at room temperature, thus improving the moldability of the polyurethane composition and reinforcing materials.

[0029] In some specific implementations, the chain extender may be a chain extender commonly used in the art, such as diols, diamines, diphenols, etc. Examples include, but are not limited to, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, cyclohexanediol, methylamine, ethylamine, hydrogenated bisphenol A, hydroquinone, etc. These chain extenders may be used alone or in combination.

[0030] In some specific implementations, the crosslinking agent can be a commonly used crosslinking agent in the art, such as polyols, polyamines, etc. Examples include, but are not limited to, trimethylolpropane, glycerol, pentaerythritol, diethanolamine, triethanolamine, ethylenediamine, phenylenediamine, sorbitol, etc. These crosslinking agents can be used alone or in combination.

[0031] In some specific embodiments, the surfactant, examples of which include, but are not limited to, for example, a polysiloxane-oxidized olefin block copolymer as its main structure, can be used alone or in combination.

[0032] In some specific implementations, the catalyst refers to a class of compounds that are catalytically active to isocyanates and active hydrogen atoms, including but not limited to amine catalysts and organometallic catalysts. Such catalysts can be used alone or in combination.

[0033] In some specific implementations, the isocyanate reactive component may also include other commonly used auxiliaries in the art, including but not limited to coupling agents, color pastes, fillers, smoke suppressants, dyes, antistatic agents, antioxidants, light stabilizers, diluents, surface wetting agents, leveling agents, thixotropic agents, viscosity reducers, plasticizers, etc.

[0034] In one specific embodiment, the molar ratio of isocyanate groups in the isocyanate component to active hydrogen atoms in the isocyanate reactive component is 95 to 105:100, such as 95:100, 100:100, 105:100, etc.

[0035] In a preferred embodiment, the isocyanate reactive component comprises, by total mass, the isocyanate reactive component:

[0036] The amount of polyether polyol 1 used is 30-50%, for example, 30%, 33%, 35%, 37%, 40%, 41%, 43%, 45%, 46%, 48%, 50%, etc.;

[0037] The amount of polyether polyol 2 used is 20% to 45%, for example, 20%, 21%, 22%, 23%, 24%, 25%, 28%, 30%, 33%, 35%, 37%, 40%, 41%, 43%, 45%, etc.

[0038] The amount of polymer polyol used is 9-10%, for example, 9%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, 10%, etc.;

[0039] The dosage of foaming agent is 0.8% to 1.3%, for example, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, etc.;

[0040] The amount of flame retardant used is 8% to 25%, for example, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc.

[0041] The dosage of chain extender is 1-5%, such as 1%, 2%, 3%, 4%, 5%, etc.;

[0042] The amount of crosslinking agent used is 1% to 3%, for example, 1%, 2%, 3%, etc.;

[0043] The amount of surfactant used is 0.3% to 0.8%, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, etc.;

[0044] The catalyst dosage is 0.5% to 1.2%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, etc.;

[0045] The amount of pigment used is 0.05% to 0.2%, for example, 0.05%, 0.1%, 0.15%, 0.2%, etc.

[0046] In a preferred embodiment, the molar ratio of isocyanate groups in the isocyanate component to active hydrogen atoms in the isocyanate reactive component of the polyurethane composition is 95 to 105:100, for example, 95:100, 98:100, 100:100, 101:100, 105:100, etc.

[0047] The polyurethane composition comprising the aforementioned polyether polyol 1, polyether polyol 2, polymer polyol, foaming agent, flame retardant, chain extender, crosslinking agent, surfactant, catalyst, pigment, and isocyanate component, when used to prepare polyurethane foam, exhibits easy handling and storage, high flame retardancy, excellent mechanical properties and low water absorption, and very excellent aging resistance and fatigue resistance. It can be used for the large-scale production of polyurethane cured track beds.

[0048] To meet the technical requirements of polyurethane cured track beds in high-altitude and cold regions for reliable fatigue resistance, low-temperature non-crystallization, flame retardancy, excellent physical properties, low water absorption, and high aging resistance, polyether polyol 1 and polyether polyol 2 are used to ensure the low-temperature non-crystallization of polyurethane foam. The introduction of polymer polyols with special side-chain structures, utilizing their strong non-covalent interactions, significantly improves the fatigue resistance of the cured track bed. This effectively extends the service life of polyurethane cured track beds, reduces manufacturing costs, simplifies construction processes, and enables economical and reliable large-scale production of polyurethane cured track bed technology.

[0049] However, several contradictory performance requirements exist in polyurethane cured track beds, such as low-temperature non-crystallization versus fatigue resistance, high elongation versus low compression set, and rigid foam-level water absorption versus flexible foam-level compression set. To effectively avoid extensive trial-and-error testing, this invention limits the amount of polyether polyol 1 (A).

[0050] 30%–50%, polyether polyol 2 dosage (B) 20%–45%, polymer polyol dosage (C)

[0051] 9% to 10%, preferably satisfying the following relationship simultaneously:

[0052]

[0053] This results in a polyurethane cured track bed that can be applied in high-altitude and cold regions, exhibiting reliable fatigue resistance, low-temperature non-crystallization, flame retardancy, excellent physical properties, low water absorption, and high aging resistance.

[0054] In the above formula, A and B are not included in the percentage. For example, when A is 50%, we directly substitute 50 into the formula. When B is 25%, we directly substitute 25 into the formula. Finally, we calculate that the content of C is 10.18, that is, the content of C is 10.18%.

[0055] In another aspect of the present invention, a method for using the polyurethane composition to prepare polyurethane foam comprises the following steps:

[0056] Step 1: Mix and stir the isocyanate components separately at 10-60°C until they are homogeneous and set aside for later use; mix and stir the isocyanate reactive components separately until they are homogeneous and set aside for later use.

[0057] Step 2: At 10-60°C, the isocyanate component and the isocyanate reactive component are mixed evenly using equipment and then injected into a mold for reaction. After the reaction is completed, the mold is opened to obtain polyurethane foam.

[0058] The preferred polyurethane foam filling density is 275–295 kg / m³. 3The preferred pouring pressure is 130–170 bar, the preferred mold temperature is 10–60°C, and the preferred holding time is 50–90 minutes.

[0059] On the other hand, a method for using the aforementioned polyurethane composition to prepare a polyurethane foam-molded and cured track bed includes the following steps:

[0060] Step 1: Mix and stir the isocyanate components separately at 10-60°C until they are homogeneous and set aside for later use; mix and stir the isocyanate reactive components separately until they are homogeneous and set aside for later use.

[0061] Step 2: At 10-60°C, the isocyanate component and the isocyanate reactive component are mixed evenly using equipment and then directly injected into the railway ballast or into a mold containing the ballast. After the reaction is completed, the polyurethane foam-molded and cured track bed is obtained directly or by opening the mold.

[0062] Step two, directly injecting railway ballast, is a construction method; the molding method involving the injection of ballast is a precast method. The temperature of the ballast and mold is 10–60℃. The curing time for the construction method is preferably 4–6 hours, and the pressure holding time for the precast method is preferably 50–90 minutes. The ballast conforms to the railway crushed stone ballast standard TB / T 2140, and the preferred ballast density is 2.5–3.1 g / cm³. 3 The preferred porosity of prefabricated ballast filling is 39%.

[0063] Regarding the specific components involved in the polyurethane composition of this invention, such as polyols and additives, unless otherwise specified, they can be used alone or in combination. Furthermore, any raw materials, processes, methods, parameters, etc., required for the preparation of each component that are not explicitly stated or described can be referenced from commonly used techniques in the art without affecting the implementation of this invention; for example, the preparation of polyether polyols and catalysts.

[0064] Unless otherwise specified, the term "hydroxyl value" in this invention refers to the average hydroxyl value of the component.

[0065] Existing patented technologies utilize non-crystalline polyether polyol components to prevent the polyurethane foam raw materials from crystallizing and settling in high-altitude and cold regions, thereby improving the processability of cured polyurethane tracks in these areas. However, these technologies overlook the significant deteriorating effect of the non-crystalline polyether polyol components on the fatigue resistance of the cured track, making it difficult to meet the fatigue resistance requirements of cured polyurethane tracks in high-altitude and cold regions.

[0066] Traditional polyurethane foam preparation technology seeks optimal process parameters through large-scale formulation trial and error. However, given the complex performance requirements of polyurethane cured track beds in high-altitude and cold regions as described in this invention, formulation design based on theoretical analysis struggles to clarify the patterns of various process parameters, necessitating extensive exploratory experiments. For instance, in the performance requirements of polyurethane cured track beds, low-temperature non-crystallization versus fatigue resistance, high elongation versus low compression set, and rigid foam-level water absorption versus flexible foam-level compression are all points of conflict between performance and formulation processes.

[0067] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0068] 1) This invention provides a polyurethane composition for use in polyurethane-cured track beds in high-altitude and cold regions. It exhibits reliable fatigue resistance, low-temperature non-crystallization, flame retardancy, excellent physical properties, low water absorption, and high aging resistance. The introduction of a polymeric polyol with a special side-chain structure ensures the low-temperature non-crystallization of the polyurethane foam, while its strong non-covalent interactions significantly improve the fatigue resistance of the cured track bed. This effectively extends the service life of the polyurethane-cured track bed, reduces manufacturing costs, simplifies construction processes, and enables economical and reliable large-scale production of polyurethane-cured track bed technology.

[0069] 2) The polyurethane foam of this invention possesses elastomer-level tensile and tear resistance and flexible foam-level compression properties, giving it both excellent elongation and compression deformation performance. Simultaneously, its rigid foam-level water absorption capacity solves the problem of high water absorption in open-cell polyurethane, further increasing the service life of the prepared polyurethane cured track bed. Detailed Implementation

[0070] The following are some examples to help the public better understand the technical solution of the present invention.

[0071] The raw materials used in the examples and comparative examples are as follows:

[0072] Isocyanate component 1, WANNATE 8605, NCO content 17.1wt%, viscosity at 25℃ 800mpa·s, Wanhua Chemical;

[0073] Isocyanate component 2, WANNATE 8609, NCO content 19.8wt%, viscosity at 25℃ 330mpa·s, Wanhua Chemical;

[0074] Isocyanate component 3, WANNATE PM200, NCO content 31.2wt%, viscosity at 25℃ 250mpa·s, Wanhua Chemical;

[0075] Polyether polyol 1-1, starting with trimethylolpropane, polymerized with propylene oxide and terminal block addition with ethylene oxide, ethylene oxide content 25wt%, hydroxyl value 20mgKOH / g;

[0076] Polyether polyol 1-2, glycerol-initiated, propylene oxide polymerization, ethylene oxide terminal block addition, ethylene oxide content 15wt%, hydroxyl value 28mgKOH / g;

[0077] Polyether polyol 1-3, glycerol-initiated, propylene oxide polymerization, ethylene oxide terminal block addition, ethylene oxide content 10wt%, hydroxyl value 40mgKOH / g;

[0078] Polyether polyol 2-1, diethylene glycol-based, random copolymer of propylene oxide and ethylene oxide, ethylene oxide content 10wt%, hydroxyl value 20mgKOH / g;

[0079] Polyether polyol 2-2, ethylene glycol-based, random copolymer of propylene oxide and ethylene oxide, ethylene oxide content 5wt%, hydroxyl value 40mgKOH / g;

[0080] Polyether polyol 2-3, starting with propylene glycol, random copolymerized with propylene oxide and ethylene oxide, ethylene oxide content 6wt%, hydroxyl value 35mgKOH / g;

[0081] Polymer polyol 1-1, starting with glycerol, hydroxyl value 20 mg KOH / g, solid content 25 wt%;

[0082] Polymer polyol 1-2, starting with trimethylolpropane, hydroxyl value 40 mg KOH / g, solid content 30 wt%;

[0083] Polymer polyols 1-3, starting with glycerol, hydroxyl value 28 mgKOH / g, solid content 45 wt%;

[0084] Polyether polyol 3, glycerol-based, hydroxyl value 35 mg KOH / g, polymerized from propylene oxide and ethylene oxide, ethylene oxide content 10%, based on the total mass of propylene oxide and ethylene oxide;

[0085] Polyether polyol 4, glycerol-based, hydroxyl value 28 mg KOH / g, polymerized from propylene oxide and ethylene oxide, ethylene oxide content 15%, based on the total mass of propylene oxide and ethylene oxide;

[0086] Polyether polyol 5, glycerol-based, hydroxyl value 45 mg KOH / g, polymerized from propylene oxide and ethylene oxide, ethylene oxide content 20%, based on the total mass of propylene oxide and ethylene oxide;

[0087] Polyether polyol 6, starting with propylene glycol, with a hydroxyl value of 28 mg KOH / g, polymerized from propylene oxide and ethylene oxide, with an ethylene oxide content of 15%, based on the total mass of propylene oxide and ethylene oxide;

[0088] Polyether polyol 7, starting with propylene glycol, with a hydroxyl value of 40 mg KOH / g, polymerized from propylene oxide and ethylene oxide, with an ethylene oxide content of 20%, based on the total mass of propylene oxide and ethylene oxide;

[0089] Polyether polyol 8, starting with propylene glycol, with a hydroxyl value of 20 mg KOH / g, polymerized from propylene oxide and ethylene oxide, with an ethylene oxide content of 10%, based on the total mass of propylene oxide and ethylene oxide;

[0090] Polymer polyol 2, starting with glycerol, 21 mg KOH / g, polymerized from propylene oxide, ethylene oxide, acrylonitrile, and styrene; solid content 40%, based on the total mass of propylene oxide, ethylene oxide, acrylonitrile, and styrene;

[0091] Polymer polyol 3, starting with glycerol, 24.5 mg KOH / g, polymerized from propylene oxide, ethylene oxide, acrylonitrile, and styrene; solid content 30%, based on the total mass of propylene oxide, ethylene oxide, acrylonitrile, and styrene;

[0092] Polymer polyol 4, starting with glycerol, 28 mg KOH / g, polymerized from propylene oxide, ethylene oxide, acrylonitrile, and styrene; solid content 20%, based on the total mass of propylene oxide, ethylene oxide, acrylonitrile, and styrene;

[0093] Foaming agent, water;

[0094] Flame retardant 1, FR212, Wanhua Chemical;

[0095] Flame retardant 2, A710, Hemu New Materials;

[0096] The specific preparation method of flame-retardant amine compounds is as follows:

[0097] FR212 and ethylenediamine (industrial grade) were selected, and a solid ruthenium-nickel bimetallic catalyst was added to the equipment. The molar ratio of FR212 to ethylenediamine was 1:2. The reaction was carried out under nitrogen protection and stirred. After reacting the resulting solution at 120°C for 24 hours, the solution was cooled to room temperature. The ruthenium-nickel bimetallic catalyst was separated by filtration. The filtrate was extracted three times with ethyl acetate. The combined organic layers were washed with saturated sodium chloride solution and dried with anhydrous magnesium sulfate to obtain the flame-retardant amine compound. According to the infrared spectroscopy results, the total amine content was 2.79 meq / g, the primary amine content was 1.44 meq / g, the secondary amine content was 1.35 meq / g, and the tertiary amine content was 0.00 meq / g.

[0098] Chain extender 1, ethylene glycol;

[0099] Chain extender 2,1,4-butanediol;

[0100] Crosslinking agent, glycerin;

[0101] Surfactant 1, WANALYST BM029, Wanhua Chemical;

[0102] Surfactant 2, WANALYST BM031, Wanhua Chemical;

[0103] Surfactant 3, B8002, Evonik Industries;

[0104] Surfactant 4, B8715, Evonik Industries;

[0105] Catalyst 1, WANALYST KC121, Wanhua Chemical;

[0106] Catalyst 2, WANALYST KC152, Wanhua Chemical;

[0107] Catalyst 3, BICAT8106, Leading Chemist;

[0108] Pigments, Promix Company;

[0109] Preparation methods of polyurethane foam samples in the examples and comparative examples:

[0110] Step 1: At 30°C, mix and stir the isocyanate components separately until homogeneous and set aside. Also mix and stir the isocyanate reactive components until homogeneous and set aside.

[0111] Step two: At 30°C, the isocyanate component and the isocyanate reactive component are mixed evenly using equipment and then injected into a mold for reaction. After the reaction is complete, the mold is opened to obtain polyurethane foam. The polyurethane foam filling density is 285 kg / m³. 3 The pouring pressure is 150 bar, the mold temperature is 50°C, and the holding time is 60 minutes.

[0112] Preparation methods of polyurethane foam-molded and cured track beds in the examples and comparative cases:

[0113] Step 1: At 30°C, mix and stir the isocyanate components separately until homogeneous and set aside. Also mix and stir the isocyanate reactive components until homogeneous and set aside.

[0114] Step two: At 30°C, the isocyanate component and the isocyanate reactive component are mixed evenly using equipment and then injected into a mold containing ballast. After the reaction is complete, a polyurethane foam-molded and cured track bed is obtained directly or by opening the mold. The ballast has a bulk density of 2.8 g / cm³. 3The ballast filling porosity is 39%, the pouring pressure is 150 bar, the mold temperature is 50℃, and the holding time is 80 minutes.

[0115] The raw materials used in the examples and comparative examples are listed in Tables 1 and 2.

[0116] Table 1 (Parts by weight)

[0117]

[0118] Table 2 (Parts by weight)

[0119]

[0120]

[0121] Performance testing

[0122] The standard for precast cured track bed was issued by China Railway Corporation. It includes the performance requirements of polyurethane foam used in precast cured track bed, as shown in Table 3.

[0123] Table 3 Performance Requirements of Polyurethane Foam for Prefabricated Cured Track Beds

[0124] Test items unit Technical Requirements Foam density <![CDATA[Kg / m 3 ]]> 285±10 10% compressive strength kPa ≥25 Tensile strength MPa ≥0.4 Elongation at break ％ ≥200 Tear strength N / m ≥800 Compression permanent deformation ％ ≤10 Oxygen Index ％ ≥26 Dry heat aging retention rate ％ ≥80 Retention rate during damp heat aging ％ ≥80 UV aging retention rate ％ ≥80 Low temperature recovery ability ％ ≥80 Water absorption rate (4d) ％ ≤25 <![CDATA[0~3×10 6 Subtotal deformation]]> mm ≤3 <![CDATA[1×10 6 ~3×10 6 Subtotal deformation]]> mm ≤0.5 <![CDATA[0~3×10 6 rate of change of substatic modulus ％ ≤50 <![CDATA[1×10 6 ~3×10 6 Rate of change of static modulus at each time ％ ≤15

[0125] The polyurethane compositions described in Examples 1-7 and Comparative Examples 1-8 were tested as follows:

[0126] (1) Foam density test standard: GB / T 6343;

[0127] (2) Compressive strength test standard: GB / T 10807;

[0128] (3) Oxygen index test standard: GB / T 2406.2;

[0129] (4) Standard for compression set test: GB / T 6669;

[0130] (5) Water absorption rate test standard: GB / T 8810;

[0131] (6) Dry heat aging and wet heat aging test standards: GB / T 9640;

[0132] (7) Ultraviolet aging test standard: GB / T 16422;

[0133] (8) Tear strength test standard: GB / T 10808;

[0134] (9) Tensile strength test standard: GB / T 6344;

[0135] (10) Standard for testing elongation at break: GB / T 6344;

[0136] (11) Low temperature performance recovery test: The low temperature performance recovery test specimen is placed at -20℃ for 168h, and then placed at 20℃ for 4h. The tensile strength and elongation at break are tested according to GB / T 6344. The outer skin of the specimen should be removed.

[0137] The test results are summarized in Tables 4 and 5.

[0138] Table 4 Performance of Examples

[0139]

[0140]

[0141] Analysis of the data in Table 4 shows that the polyurethane composition of the present invention meets the requirements for polyurethane used in precast cured track beds, and the foam density of the polyurethane composition of the present invention is 285±10Kg / m³. 3 Within the specified range, the compressive strength is above 47 MPa, the tensile strength is above 540 kPa, the elongation at break is above 206%, the tear strength is above 842 N / m, the compression set is below 10%, the dry heat aging retention rate is above 90%, the wet heat aging retention rate is above 92%, the low temperature recovery ability is above 92%, the water absorption rate is below 15%, the oxygen index is above 26%, and the range is 0–3 × 10⁻⁶. 6 The cumulative deformation is less than 2.8 mm, 1×10 6 ~3×10 6 The cumulative deformation is below 0.40 mm, ranging from 0 to 3 × 10⁻⁶ mm. 6 The rate of change of the substatic modulus is below 45%, 1×10 6 ~3×10 6 The rate of change of static modulus is below 14% for each iteration.

[0142] In addition, the polyurethane composition of the present invention does not contain any room temperature solid polyols or solid flame retardants, does not precipitate or crystallize at room temperature, has good storage stability and processability, and the isocyanate component and the isocyanate reactive component have excellent compatibility. The foam prepared from the polyurethane composition has excellent mechanical strength, toughness, deformation resistance, aging resistance and flame retardant properties, and can simultaneously meet the comprehensive requirements of China Railway Corporation for the mechanical properties, flame retardancy and water absorption of polyurethane foam for prefabricated cured track beds.

[0143] Table 5 Comparative Example Performance

[0144]

[0145]

[0146] Table 5 presents the performance test results of each comparative example. Analysis of Comparative Examples 1-8 shows that although they meet the requirements for polyurethane used in precast cured track beds in terms of foam density, 10% compressive strength, tensile strength, elongation at break, tear strength, compression set, dry heat aging, wet heat aging, low-temperature recovery, water absorption (4d), and oxygen index, they fall short in the range of 0–3 × 10⁻⁶. 6 The sum of 1×10 6 ~3×10 6 The cumulative deformation and 0~3×10 6 The sum of 1×10 6 ~3×10 6 The rate of change of the static modulus does not fully meet the requirements for polyurethane used in prefabricated cured track beds.

[0147] In existing patents CN201410816023.X (Example 1), CN201510556783.6 (Example 1), and CN202110126614.4 (Example 1), the components are prone to crystallization when there is no raw material preheating step, and the raw materials may even fail to mix, resulting in the inability to form the part.

[0148] The present invention has been illustrated with the above embodiments to explain the detailed method of the present invention. However, the present invention is not limited to the detailed method described above, that is, it does not mean that the present invention must rely on the detailed method described above to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A high fatigue-resistant polyurethane composition, characterized in that, It is obtained by reacting an isocyanate component and an isocyanate reactive component, wherein the isocyanate reactive component comprises: polyether polyol 1, polyether polyol 2, polymer polyol, foaming agent, flame retardant, chain extender, crosslinking agent, surfactant, catalyst, and pigment; wherein, The polyether polyol 1 has an average functionality of 2-4.5 and a hydroxyl value of 10-200 mgKOH / g. It is obtained by reacting ethylene oxide and propylene oxide, with an ethylene oxide content of 10-25 wt%, based on the total mass of propylene oxide and ethylene oxide being 100%. The polyether polyol 2 has an average functionality of 1.5-3 and a hydroxyl value of 10-200 mgKOH / g. It is obtained by reacting ethylene oxide and propylene oxide, with an ethylene oxide content of 5-10 wt%, based on the total mass of propylene oxide and ethylene oxide being 100%. The polymer polyol, namely the graft copolymer polyether polyol, has an average functionality of 2-4.5, a hydroxyl value of 15-50 mgKOH / g, and a solid content of 20-50 wt%. Based on the total mass of the isocyanate reactive components, the amount of polyether polyol 1 A in the isocyanate reactive components is 30%~50%, the amount of polyether polyol 2 B is 20%~45%, and the amount of polymer polyol C is 9%~10%.

2. The high fatigue resistance polyurethane composition according to claim 1, characterized in that, The polyether polyol 1 has an average functionality of 2.5-3.5 and a hydroxyl value of 20-40 mgKOH / g. The polyether polyol 2 has an average functionality of 1.5 to 2.5 and a hydroxyl value of 20 to 40 mg KOH / g. The polymer polyol, namely the graft copolymer polyether polyol, has an average functionality of 3, a hydroxyl value of 20~40 mgKOH / g, and a solid content of 25~45 wt%.

3. The high fatigue resistance polyurethane composition according to claim 1, characterized in that, The polyether polyol 1 is polymerized from a polyol initiator, ethylene oxide, and propylene oxide. The initiator used is selected from at least one of ethylene glycol, propylene glycol, 1,4-butanediol, dipropylene glycol, diethylene glycol, triethylene glycol, bisphenol A, glycerol, trimethylolpropane, diethanolamine, triethanolamine, ethylenediamine, toluenediamine, pentaerythritol, sorbitol, xylitol, and sucrose.

4. The high fatigue resistance polyurethane composition according to claim 3, characterized in that, The polyether polyol 1 is initiated by polyol polymerization, followed by propylene oxide polymerization and end-phase ethylene oxide block addition.

5. The high fatigue resistance polyurethane composition according to claim 1, characterized in that, The polyether polyol 2 is polymerized from a polyol initiator, ethylene oxide, and propylene oxide. The initiator is selected from at least one of ethylene glycol, propylene glycol, 1,4-butanediol, dipropylene glycol, diethylene glycol, triethylene glycol, bisphenol A, glycerol, trimethylolpropane, diethanolamine, triethanolamine, ethylenediamine, toluenediamine, and pentaerythritol.

6. The high fatigue resistance polyurethane composition according to claim 1, characterized in that, The polymer polyol is a graft copolymer polyether polyol obtained by reacting polyether polyol and vinyl monomer.

7. The high fatigue resistance polyurethane composition according to claim 6, characterized in that, The polyether polyol is selected from at least one of polyethylene oxide polyol, polypropylene oxide polyol, and polyethylene oxide-propylene oxide copolyol; and / or The vinyl monomer is selected from at least one of acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl acrylates, and alkyl acrylates.

8. The high fatigue resistance polyurethane composition according to claim 7, characterized in that, The vinyl monomer is selected from acrylonitrile and / or styrene.

9. The high fatigue resistance polyurethane composition according to claim 1, characterized in that, The foaming agent is a physical foaming agent or a chemical foaming agent; and / or The flame retardant is selected from at least one of the following: halogenated phosphate flame retardants, phosphate flame retardants, halogenated hydrocarbons and other halogenated flame retardants, melamine and its salts, reactive flame retardants, and inorganic flame retardants.

10. The high fatigue resistance polyurethane composition according to claim 9, characterized in that, The foaming agent is selected from one or more of water, monochlorodifluoromethane, monochloromonofluoromethane, dichlorodifluoromethane, trichlorofluoromethane, butane, pentane, cyclopentane, hexane, cyclohexane, heptane, air, CO2, and N2; and / or The flame retardant is selected from liquid flame retardants with a viscosity of 40~800 mpa·s at 25°C.

11. The high fatigue resistance polyurethane composition according to claim 10, characterized in that, The foaming agent is water; and / or The flame retardant is a liquid flame retardant with a viscosity of 60~400 mPa·s at 25°C.

12. The high fatigue resistance polyurethane composition according to claim 10, characterized in that, The flame retardant is composed of flame retardant 1 and flame retardant 2; flame retardant 1 is a reactive flame retardant; flame retardant 2 is one or both of halogenated phosphate flame retardants and phosphate flame retardants.

13. The high fatigue resistance polyurethane composition according to claim 12, characterized in that, The flame retardant 1 is selected from at least one of tris(dipropylene glycol) phosphite, diethyl N,N-di(2-hydroxyethyl)aminomethylenephosphonate, dimethyl N,N-di(2-hydroxyethyl)aminomethylphosphonate, and Wanhua Chemical's FR212; the flame retardant 2 is selected from at least one of tris(2-chloroethyl) phosphate, (2-chloropropyl) phosphate, di(3-bromo-2,2-dimethylpropyl) phosphate, dimethyl methyl phosphate, diethyl ethyl phosphate, dimethyl propyl phosphate, triethyl phosphate, triphenyl phosphate, and tricresyl phosphate.

14. The high fatigue resistance polyurethane composition according to claim 1, characterized in that, The chain extender is selected from at least one of diols, diamines, and diphenols; and / or The crosslinking agent is selected from at least one of polyols and polyamines; and / or The surfactant is at least one of polysiloxane-oxidized olefin block copolymers; and / or The catalyst is selected from at least one of amine catalysts and organometallic catalysts.

15. The high fatigue resistance polyurethane composition according to claim 14, characterized in that, The chain extender is selected from at least one of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, cyclohexanediol, hydrogenated bisphenol A, hydroquinone, ethylenediamine, and phenylenediamine; and / or The crosslinking agent is selected from at least one of trimethylolpropane, glycerol, pentaerythritol, diethanolamine, triethanolamine, and sorbitol.

16. The high fatigue resistance polyurethane composition according to any one of claims 1 to 15, characterized in that, The isocyanate reactive component further includes an auxiliary agent selected from at least one of coupling agents, fillers, smoke inhibitors, dyes, antistatic agents, antioxidants, light stabilizers, diluents, surface wetting agents, leveling agents, thixotropic agents, viscosity reducers, and plasticizers.

17. The high fatigue resistance polyurethane composition according to claim 16, characterized in that, Based on the total mass of the isocyanate reactive component, the isocyanate reactive component comprises: Polyether polyol 1, 30~50%; Polyether polyol 2, 20~45%; Polymer polyols, 9-10%; Foaming agent, 0.8~1.3%; Flame retardant, 8-25%; Chain extender, 1-5%; Crosslinking agent, 1-3%; Surfactant, 0.3~0.8%; Catalyst, 0.5~1.2%; Pigment, 0.05~0.2%.

18. The high fatigue resistance polyurethane composition according to claim 17, characterized in that, The molar ratio of isocyanate groups in the isocyanate component to active hydrogen atoms in the isocyanate reactive component of the polyurethane composition is 95~105:

100.

19. A method for preparing a polyurethane foam-molded and cured track bed using the high fatigue-resistant polyurethane composition according to any one of claims 1 to 18, characterized in that, It includes the following steps: Step 1: Mix the isocyanate component and the isocyanate reactive component thoroughly at 10~60℃ and set aside. Step 2: At 10~60℃, the isocyanate component and the isocyanate reactive component are mixed evenly by the equipment and then directly injected into the railway ballast or into a mold containing the ballast. After the reaction is completed, the polyurethane foamed and cured track bed is obtained directly or by opening the mold.

20. The application of a polyurethane foam-molded and cured track bed prepared by the method of claim 19 in railway tracks.

21. The application according to claim 20, characterized in that, Used for curing track beds in high-altitude and cold regions.

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