Single-component sealant suitable for caulking of ballastless track of railway and preparation method of single-component sealant

Abstract

The invention discloses a single-component sealant suitable for caulking of a ballastless track of a railway and a preparation method of the single-component sealant. The single-component sealant comprises the following components in parts by weight: 90-120 parts of resin, 70-90 parts of a plasticizer, 120-190 parts of nano calcium carbonate, 20-80 parts of ground calcium carbonate, 10-30 parts of titanium dioxide, 1-8 parts of a thixotropic agent, 1-5 parts of an ultraviolet light absorber, 1-5 parts of a light stabilizer, 1-6 parts of a dehydrating agent, 1-6 parts of a coupling agent and 10-30 parts of a catalyst. The preparation method comprises the following steps: mixing the resin and the plasticizer in a stirrer to form a first mixture; gradually adding nano calcium carbonate, heavy calcium carbonate and titanium dioxide in three stages, and continuously stirring to form a second mixture; adding an ultraviolet light absorber and a light stabilizer, and continuously stirring; sequentially adding a dehydrating agent, a coupling agent, a thixotropic agent and a catalyst, and stirring; and finally, carrying out fine treatment by using a defoaming machine. The method can be used for preparing the single-component sealant with excellent performance.

Description

Technical Field

[0001] This invention belongs to the field of sealant technology, specifically relating to a single-component sealant suitable for caulking joints in railway ballastless tracks and its preparation method. Background Technology

[0002] Ballastless track is an advanced track type that uses an integral structure of concrete and asphalt mixture to replace the traditional crushed stone track bed. It boasts advantages such as high smoothness, high stability, strong durability, and low maintenance requirements, and is gradually becoming the development trend for future high-speed train tracks. As the core structure of high-speed railways, the safety and durability of ballastless track directly determine the operational safety and service life of the line. The base and track slab of ballastless track adapt to temperature deformation through joints, which are the weakest points in the track's waterproofing system. Long-term dynamic loads from high-speed trains, structural expansion and contraction due to diurnal temperature variations, ultraviolet radiation exposure, and rainwater erosion all place stringent demands on the sealing effect of these joints. If the sealing material is inadequate, problems such as cracking, delamination, and elasticity failure can easily occur, allowing rainwater and impurities to easily seep into the track interior. This can lead to freeze-thaw damage to the base concrete, steel corrosion, and cracking of the track slab, severely impacting track smoothness and even threatening train safety. Therefore, the performance of the joint sealing material is crucial to ensuring the structural safety and durability of ballastless track.

[0003] MS sealant, with its superior performance, effectively addresses the core risks of sealing joints in ballastless tracks. Its ability to cure upon contact with air and moisture without complex mixing ensures convenient and efficient application, preventing seal failure due to improper handling. Simultaneously, MS sealant possesses excellent adhesion, firmly bonding to substrates such as concrete bases and subgrade structures, effectively preventing joint delamination and water seepage. Its superior elasticity and weather resistance allow it to withstand long-term thermal expansion and contraction of the track structure, resisting the effects of ultraviolet radiation and extreme temperatures, preventing material cracking and aging. Good water and chemical resistance prevent internal structural corrosion caused by moisture penetration, fundamentally reducing the risk of track defects and providing reliable protection for the structural safety and long-term durability of ballastless tracks. Traditional MS sealant preparation requires a large amount of inorganic filler, increasing production costs and putting pressure on natural mineral resources. Therefore, there is an urgent need for an MS sealant that can effectively reduce production costs and alleviate pressure on natural mineral resources while maintaining sealant performance, along with its preparation method and application. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a single-component sealant suitable for caulking joints in railway ballastless tracks and its preparation method. This sealant possesses excellent adhesion, firmly bonding to concrete substrates such as the ballastless track base and track slab, preventing interface debonding. It also blocks rainwater and impurities from seeping into the track interior through the joints, reducing the risk of freeze-thaw damage to the base concrete and steel corrosion. The sealant exhibits strong weather resistance, resisting the effects of ultraviolet radiation and alternating high and low temperatures, extending the service life of the sealing material and reducing problems such as track slab cracking caused by material failure. Furthermore, the sealant possesses good fatigue resistance, capable of withstanding the vibration and impact of high-speed train dynamic loads for extended periods without significant performance degradation, thus reducing potential safety hazards. The product's preparation process is simple, ensuring the sealing performance of ballastless tracks in complex environments and meeting the long-term stability and durability requirements of track structures.

[0005] To achieve the above objectives, the present invention provides a one-component sealant suitable for caulking joints in railway ballastless tracks. The raw materials of the one-component MS sealant, by weight, include the following components: 90-120 parts of silane-modified polyether resin, 70-90 parts of plasticizer, 120-190 parts of nano-calcium carbonate, 20-80 parts of heavy calcium carbonate, 10-30 parts of titanium dioxide, 1-8 parts of thixotropic agent, 1-5 parts of ultraviolet absorber, 1-5 parts of light stabilizer, 1-6 parts of dehydrating agent, 1-6 parts of coupling agent, and 10-30 parts of catalyst. The nano-calcium carbonate has a mesh size of 4000-5000 mesh; The mesh size of the heavy calcium carbonate is 200-800 mesh; The titanium dioxide has a mesh size of 100 to 500 mesh.

[0006] Furthermore, in order to obtain a sealant with even better performance, the sealant contains 100 parts of silane-modified polyether resin, 85 parts of plasticizer, 145 parts of nano-calcium carbonate, 45 parts of heavy calcium carbonate, 15 parts of titanium dioxide, 3.5 parts of thixotropic agent, 1 part of ultraviolet absorber, 1 part of light stabilizer, 3.5 parts of dehydrating agent, 3.5 parts of coupling agent, and 16.5 parts of catalyst.

[0007] Furthermore, to ensure the sealant possesses better adhesion and basic mechanical properties, and to guarantee stable adsorption through chemical bonding between the sealant and the substrate surface, the silane-modified polyether resin used is KANEKA MS POLYMER™ S327 from Kaneka Corporation of Japan. The chemical structure of KANEKA MS POLYMER™ S327 features a polyether main chain with methoxysilyl groups at the ends. The pH value of KANEKA MS POLYMER™ S327 liquid resin is between 6.0 and 8.0, and its viscosity is between 25,000 and 43,000 mPa·s.

[0008] Furthermore, to ensure the acquisition of a sealant with superior overall performance, the plasticizer is diisodecyl phthalate; the thixotropic agent is a micronized polyamide rheology modifier; the ultraviolet absorber is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; the light stabilizer is 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole; the dehydrating agent is vinyltrimethoxysilane; the coupling agent is N-aminoethyl-3-aminopropylmethyldimethoxysilane; and the catalyst is diisodecyl phthalate, tin 2-ethylhexanoate, and dodecylamine.

[0009] The raw materials of the single-component MS sealant provided by this invention include a specific proportion of silane-modified polyether resin, plasticizer, nano-calcium carbonate, heavy calcium carbonate, titanium dioxide, thixotropic agent, ultraviolet absorber, light stabilizer, dehydrating agent, coupling agent, and catalyst. The silane-modified polyether resin provides high elasticity and adhesion, while the nano-calcium carbonate and heavy calcium carbonate form a dense filled network. Simultaneously, the thixotropic agent ensures anti-sagging properties, and the ultraviolet absorber and light stabilizer synergistically delay aging. In particular, the presence of titanium dioxide not only reflects ultraviolet light and forms a double protection with the ultraviolet absorber, greatly reducing the risk of resin chain breakage, but also significantly reduces light penetration due to its high refractive index. Furthermore, it synergistically works with the light stabilizer to inhibit yellowing. Therefore, the above combination results in a single-component MS sealant that possesses excellent adhesion, high elasticity and deformability, superior weather resistance, good water and chemical resistance, and low pollution and environmental friendliness. When applied to caulking ballastless tracks, it can firmly bond with various substrates such as concrete and metal, and is not prone to detachment; it has high elongation, which can adapt to the thermal expansion and contraction, vibration and other deformations of the substrate, and maintain the sealing effect for a long time; it can resist harsh environments such as ultraviolet exposure, alternating high and low temperatures (-20℃~100℃), and rain erosion, and is not prone to aging and cracking; it prevents moisture penetration and has a certain tolerance to alkaline substances released from concrete, and is not easily corroded; it does not contain harmful substances such as isocyanates and formaldehyde, and no toxic gases are released during the curing process, making it environmentally friendly and friendly to construction workers.

[0010] This sealant has strong adhesion and high elasticity, which can accurately adapt to the deformation and sealing requirements of ballastless track joints. It is environmentally friendly and non-toxic, and is easy to apply and has strong weather resistance, providing a green and safe guarantee for ballastless track joint caulking.

[0011] This invention also provides a method for preparing a one-component sealant suitable for caulking joints in railway ballastless tracks, comprising the following steps: Step 1: Put 90-120 parts of silane-modified polyether resin and 70-90 parts of plasticizer into a mixer and stir at 500 rpm for 5 minutes; Step 2: Add 120-190 parts of nano calcium carbonate, 20-80 parts of heavy calcium carbonate, and 10-30 parts of titanium dioxide in three batches. After mixing, increase the speed stepwise to 1000 rpm, 1500 rpm, and 2000 rpm, and continue stirring for 5 minutes at each speed to evenly disperse the filler. Step 3: Add 1-5 parts of UV absorber, 1-5 parts of light stabilizer and 1-8 parts of thixotropic agent, and stir at 2700 rpm for 60 min; Step 4: Add 1-6 parts of dehydrating agent, 1-6 parts of coupling agent and 1-6 parts of catalyst every 5 minutes to obtain mixed raw materials; Step 5: After stirring evenly, put the mixed raw materials into a vacuum degassing machine, maintain atmospheric pressure at -0.09MPa to 0.1MPa, and degas at 1000rpm for 15 minutes. After vacuum degassing treatment, a single-component sealant suitable for caulking railway ballastless tracks is obtained.

[0012] Furthermore, in order to obtain a sealant with even better performance, in step one, 100 parts of silane-modified polyether resin and 85 parts of plasticizer are added; in step two, 145 parts of nano-calcium carbonate, 45 parts of heavy calcium carbonate and 15 parts of titanium dioxide are added in three batches; in step three, 1 part of ultraviolet absorber, 1 part of light stabilizer and 3.5 parts of thixotropic agent are added; in step four, 3.5 parts of dehydrating agent, 3.5 parts of coupling agent and 6.5 parts of catalyst are added.

[0013] Furthermore, to ensure the acquisition of a sealant with excellent mechanical properties, weather resistance, and density, in step one, the silane-modified polyether resin is KANEKA MS POLYMER™ S327, and the plasticizer is diisodecyl phthalate; in step three, the ultraviolet absorber is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, the light stabilizer is 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and the thixotropic agent is micronized polyamide rheology modifier; in step four, the dehydrating agent is vinyltrimethoxysilane, the coupling agent is N-aminoethyl-3-aminopropylmethyldimethoxysilane, and the catalyst is diisodecyl phthalate, tin 2-ethylhexanoate, and dodecylamine.

[0014] The preparation method of the single-component MS sealant for caulking railway ballastless track provided by this invention has a simple process flow. It adopts a step-by-step stirring process combined with dispersing filler and step-by-step increase of rotation speed to prepare the single-component MS sealant for caulking railway ballastless track. This can effectively ensure the uniform dispersion of each component and enable sufficient mixing between multiple components. At the same time, it can promote effective coupling between the components. Finally, vacuum degassing can effectively eliminate micropores. As a result, the S327 resin of the specific component can work more synergistically with the other specific materials. Specifically, KANEKA MS POLYMER™ S327 itself has excellent high elasticity and adhesion. Combined with nano calcium carbonate to fill micropores and heavy calcium carbonate to reduce shrinkage, it can form a high-density structure and effectively balance tensile strength and elongation at break, significantly improving the performance of the sealant. Furthermore, the addition of titanium dioxide fills the gaps between nano-calcium carbonate particles, forming a denser structure and further improving the sealant's pressure resistance. Simultaneously, the hydroxyl groups on the titanium dioxide surface react with the coupling agent, enhancing interfacial bonding and reducing stress concentration. Moreover, the simultaneous presence of ultraviolet absorbers and light stabilizers synergistically delays aging. Based on this, the dispersed addition of titanium dioxide not only reflects ultraviolet light, forming a dual protective barrier with the ultraviolet absorber and significantly reducing the risk of resin chain breakage, but also, due to its high refractive index, substantially reduces light transmittance. This, in turn, synergistically with the light stabilizer to inhibit yellowing, significantly improving anti-aging capabilities. Therefore, this process not only effectively ensures the sealant's performance but also significantly improves production efficiency and reduces production costs.

[0015] Compared with the prior art, the present invention has the following advantages: 1. Environmental benefits: The MS sealant of this invention does not contain harmful substances such as formaldehyde and isocyanate, is solvent-free, and has a VOC emission level lower than the industry standard. It is harmless to the environment and the health of construction workers, and meets the environmental protection requirements of modern railway construction. At the same time, the MS sealant does not contain volatile solvents or easily migrating plasticizers, does not contain silicone oil or silicone resin, and will not attract dust from the air to cause pollution. It can keep the joints of ballastless track clean, which is conducive to the long-term maintenance and aesthetics of the track.

[0016] 2. Outstanding weather resistance and durability: The MS sealant of this invention has a stable molecular structure. Through the synergistic effect of titanium dioxide, ultraviolet absorbers and light stabilizers, it can effectively resist the erosion of natural factors such as ultraviolet rays, rain, and moisture. After 300 days of natural environmental aging, its mechanical properties retain more than 90%, which can reduce the maintenance frequency of ballastless tracks.

[0017] 3. Performance Advantages: According to GB / T13477, the mechanical test of this sealant showed a tensile strength of 1.23 MPa, an elongation at break of 824%, a 100% modulus of 0.149 MPa, an elastic recovery rate of 86.60%, and a surface drying time of 108 min. This means that the single-component MS sealant achieves an elastic recovery rate of over 85% and an elongation rate of over 800%, meeting the standard requirements for sealants used in ballastless track joints. This demonstrates excellent performance in terms of bond strength, tensile strength, elasticity, and curing speed, and can meet the needs of different application scenarios.

[0018] This method is simple to implement and has obvious advantages in sealant performance. Through the synergistic effect of multiple materials such as silane-modified polyether polymer, titanium dioxide and other specific components, it can prepare a single-component sealant with excellent performance in terms of bonding strength, tensile strength, elasticity and plasticity, weather resistance and curing speed, which solves the problem of insufficient performance of ballastless track caulking materials and is suitable for the stringent requirements of ballastless track caulking and sealing. Attached Figure Description

[0019] Figure 1 This is a flowchart of the preparation method in this invention; Figure 2 These are the engineering stress-strain curves of the sealants in Examples 1-3 and Comparative Examples 1-2 of this invention; Figure 3 It is the 100% tensile modulus of the sealants in Examples 1-3 and Comparative Examples 1-2 of this invention; Figure 4 The tensile strength of the sealants in Examples 1-3 and Comparative Examples 1-2 of this invention; Figure 5 It refers to the elongation at break of the sealant in Examples 1-3 and Comparative Examples 1-2 of this invention. Detailed Implementation

[0020] The present invention will be further described below.

[0021] like Figure 1 As shown, the present invention provides a one-component sealant suitable for caulking joints in railway ballastless tracks. The raw materials of the one-component MS sealant include the following components by weight: 90-120 parts of silane-modified polyether resin, 70-90 parts of plasticizer, 120-190 parts of nano-calcium carbonate, 20-80 parts of heavy calcium carbonate, 10-30 parts of titanium dioxide, 1-8 parts of thixotropic agent, 1-5 parts of ultraviolet absorber, 1-5 parts of light stabilizer, 1-6 parts of dehydrating agent, 1-6 parts of coupling agent, and 10-30 parts of catalyst. The nano-calcium carbonate has a mesh size of 4000-5000 mesh; The mesh size of the heavy calcium carbonate is 200-800 mesh; The titanium dioxide has a mesh size of 100 to 500 mesh.

[0022] To obtain a sealant with superior performance, the composition includes 100 parts of silane-modified polyether resin, 85 parts of plasticizer, 145 parts of nano-calcium carbonate, 45 parts of heavy calcium carbonate, 15 parts of titanium dioxide, 3.5 parts of thixotropic agent, 1 part of ultraviolet absorber, 1 part of light stabilizer, 3.5 parts of dehydrating agent, 3.5 parts of coupling agent, and 16.5 parts of catalyst.

[0023] To ensure the sealant possesses superior adhesion and fundamental mechanical properties, and to guarantee stable adsorption through chemical bonding between the sealant and the substrate surface, the silane-modified polyether resin used is KANEKA MS POLYMER™ S327 from Kaneka Corporation of Japan. KANEKA MS POLYMER™ S327 has a polyether-based main chain with methoxysilyl groups at the ends, making it a suitable base resin for producing high-performance moisture-curing adhesives and sealants. It can be used to prepare sealants through either hot or cold processing. The liquid resin of KANEKA MS POLYMER™ S327 has a pH value between 6.0 and 8.0, offering a wide formulation range. Its viscosity, between 25,000 and 43,000 mPa·s, facilitates mixing, stirring, and coating during sealant preparation, and maintains stable performance under various process conditions. KANEKA MS POLYMER™ S327 features high elongation and high displacement capacity, enabling the sealant to accommodate significant joint deformation. It also boasts low modulus, long-lasting durability, reactivity, and storage stability, ensuring excellent sealing performance and physical-mechanical properties over extended use. Furthermore, this product meets environmental requirements, being low in VOCs and isocyanates, making the prepared sealant more environmentally friendly.

[0024] At room temperature, the methoxysilyl group (-Si-OCH3) at the end of the KANEKA MS POLYMER™ S327 molecular chain undergoes a hydrolysis reaction with moisture in the air to generate silanol (Si-OH) and methanol (CH3OH). The reaction equation is: Si-OCH3 + H2O → Si-OH + CH3OH.

[0025] The silanol groups (Si-OH) generated by hydrolysis undergo condensation reactions with each other or with unhydrolyzed methoxysilyl groups (-Si-OCH3) to form silicon-oxygen bonds (Si-O-Si), releasing water or methanol in the process. The reaction equations are: 2Si-OH → Si-O-Si + H2O, Si-OH + Si-OCH3 → Si-O-Si + CH3OH. Through continuous hydrolysis and condensation reactions, a three-dimensional network structure is formed between the molecular chains of KANEKA MS POLYMER™ S327, transforming the sealant from a liquid to a solid elastomer.

[0026] To fully utilize the properties of each component of the sealant and obtain a sealant with superior performance, the plasticizer is diisodecyl phthalate, which exhibits strong high and low temperature resistance, hydrolysis resistance, and acid and alkali resistance, making it more suitable for extreme temperature environments; it has low volatility and low migration, reducing hardening and cracking caused by component loss and extending service life; it mixes well with various commonly used sealant base materials such as PVC, butyl rubber, and silicone rubber, eliminating the need for additional compatibilizers and simplifying the production formulation; the thixotropic agent is a micronized polyamide rheology modifier; and the ultraviolet absorber is bis(2,2,6,6) Tetramethyl-4-piperidinyl) sebacate effectively absorbs and quenches ultraviolet (UV) energy, captures free radicals generated by UV irradiation, and inhibits the photo-oxidative degradation reaction of the sealant, significantly improving its weather resistance and extending its service life by 20%-30%. The light stabilizer, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, directly absorbs UV radiation irradiated to the sealant surface, preventing UV-induced molecular chain breakage in the sealant base material and preventing aging problems such as hardening, cracking, and decreased elasticity. By blocking the UV degradation pathway, it indirectly protects the plasticizers, adhesives, and other additives inside the sealant from UV decomposition, extending the overall service life of the sealant. The dehydrating agent, vinyltrimethoxysilane, preferentially reacts with trace amounts of moisture in the sealant raw materials to generate stable siloxane bonds (-Si-O-Si-) and methanol, preventing moisture from reacting with the curing agent to generate bubbles. The silanol groups generated by hydrolysis can undergo condensation reactions with active groups such as hydroxyl and amino groups in the sealant base material to form a denser cross-linked network, thereby improving the mechanical strength and elasticity of the sealant. The coupling agent is N-aminoethyl-3-aminopropylmethyldimethoxysilane, whose diamino groups can be adsorbed on the surface of inorganic fillers such as calcium carbonate and silica, neutralizing the polarity of the fillers and enabling them to be uniformly dispersed in non-polar or weakly polar organic base materials, thus avoiding filler agglomeration that leads to particulate matter and uneven mechanical properties in the sealant. The silanol groups form stable siloxane bonds (-Si-O-substrate) with the hydroxyl groups on the substrate surface, and the diamino groups react with the sealant base material to build a stable chemical bonding layer at the "substrate-sealant" interface, significantly improving the adhesion strength. The catalysts are diisodecyl phthalate, tin 2-ethylhexanoate, and dodecylamine. Diisodecyl phthalate can lower the glass transition temperature of the sealant base material, making it change from a hard and brittle state to a soft and elastic one. Tin 2-ethylhexanoate mainly catalyzes the silanol condensation reaction of silicone sealant and the crosslinking reaction of isocyanate and hydroxyl groups in polyurethane sealant, promoting the sealant to change from a liquid state to an elastic solid state. Dodecylamine mainly catalyzes the curing reaction of polyurethane sealant, and has both catalytic and coupling auxiliary effects. While promoting curing, it can slightly improve the initial adhesion between the sealant and the substrate.

[0027] The raw materials of the single-component MS sealant provided by this invention include a specific proportion of silane-modified polyether resin, plasticizer, nano-calcium carbonate, heavy calcium carbonate, titanium dioxide, thixotropic agent, ultraviolet absorber, light stabilizer, dehydrating agent, coupling agent, and catalyst. The silane-modified polyether resin provides high elasticity and adhesion, while the nano-calcium carbonate and heavy calcium carbonate form a dense filled network. Simultaneously, the thixotropic agent ensures anti-sagging properties, and the ultraviolet absorber and light stabilizer synergistically delay aging. In particular, the presence of titanium dioxide not only reflects ultraviolet light and forms a double protection with the ultraviolet absorber, greatly reducing the risk of resin chain breakage, but also significantly reduces light penetration due to its high refractive index. Furthermore, it synergistically works with the light stabilizer to inhibit yellowing. Therefore, the above combination results in a single-component MS sealant that possesses excellent adhesion, high elasticity and deformability, superior weather resistance, good water and chemical resistance, and low pollution and environmental friendliness. When applied to caulking ballastless tracks, it can firmly bond with various substrates such as concrete and metal, and is not prone to detachment; it has high elongation, which can adapt to the thermal expansion and contraction, vibration and other deformations of the substrate, and maintain the sealing effect for a long time; it can resist harsh environments such as ultraviolet exposure, alternating high and low temperatures (-20℃~100℃), and rain erosion, and is not prone to aging and cracking; it prevents moisture penetration and has a certain tolerance to alkaline substances released from concrete, and is not easily corroded; it does not contain harmful substances such as isocyanates and formaldehyde, and no toxic gases are released during the curing process, making it environmentally friendly and friendly to construction workers.

[0028] This sealant has strong adhesion and high elasticity, which can accurately adapt to the deformation and sealing requirements of ballastless track joints. It is environmentally friendly and non-toxic, and is easy to apply and has strong weather resistance, providing a green and safe guarantee for ballastless track joint caulking.

[0029] This invention also provides a method for preparing a one-component sealant suitable for caulking joints in railway ballastless tracks, comprising the following steps: Step 1: Put 90-120 parts of silane-modified polyether resin and 70-90 parts of plasticizer into a mixer and stir at 500 rpm for 5 minutes; Step 2: Add 120-190 parts of nano calcium carbonate, 20-80 parts of heavy calcium carbonate, and 10-30 parts of titanium dioxide in three batches. After mixing, increase the speed stepwise to 1000 rpm, 1500 rpm, and 2000 rpm, and continue stirring for 5 minutes at each speed to evenly disperse the filler. Step 3: Add 1-5 parts of UV absorber, 1-5 parts of light stabilizer and 1-8 parts of thixotropic agent, and stir at 2700 rpm for 60 min; Step 4: Add 1-6 parts of dehydrating agent, 1-6 parts of coupling agent and 1-6 parts of catalyst every 5 minutes to obtain mixed raw materials; Step 5: After stirring evenly, put the mixed raw materials into a vacuum degassing machine, maintain atmospheric pressure at -0.09MPa to 0.1MPa, and degas at 1000rpm for 15 minutes. After vacuum degassing treatment, a single-component sealant suitable for caulking railway ballastless tracks is obtained.

[0030] To obtain a sealant with superior performance, in step one, 100 parts of silane-modified polyether resin and 85 parts of plasticizer are added; in step two, 145 parts of nano-calcium carbonate, 45 parts of heavy calcium carbonate, and 15 parts of titanium dioxide are added in three batches; in step three, 1 part of ultraviolet absorber, 1 part of light stabilizer, and 3.5 parts of thixotropic agent are added; in step four, 3.5 parts of dehydrating agent, 3.5 parts of coupling agent, and 6.5 parts of catalyst are added.

[0031] To ensure the acquisition of a sealant with excellent mechanical properties, weather resistance, and density, in step one, the silane-modified polyether resin is KANEKA MS POLYMER™ S327, and the plasticizer is diisodecyl phthalate; in step three, the ultraviolet absorber is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, the light stabilizer is 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and the thixotropic agent is micronized polyamide rheology modifier; in step four, the dehydrating agent is vinyltrimethoxysilane, the coupling agent is N-aminoethyl-3-aminopropylmethyldimethoxysilane, and the catalysts are diisodecyl phthalate, tin 2-ethylhexanoate, and dodecyl primary amine.

[0032] The preparation method of the single-component MS sealant for caulking railway ballastless track provided by this invention has a simple process flow. It adopts a step-by-step stirring process combined with dispersing filler and step-by-step increase of rotation speed to prepare the single-component MS sealant for caulking railway ballastless track. This can effectively ensure the uniform dispersion of each component and enable sufficient mixing between multiple components. At the same time, it can promote effective coupling between the components. Finally, vacuum degassing can effectively eliminate micropores. As a result, the S327 resin of the specific component can work more synergistically with the other specific materials. Specifically, KANEKA MS POLYMER™ S327 itself has excellent high elasticity and adhesion. Combined with nano calcium carbonate to fill micropores and heavy calcium carbonate to reduce shrinkage, it can form a high-density structure and effectively balance tensile strength and elongation at break, significantly improving the performance of the sealant. Furthermore, the addition of titanium dioxide fills the gaps between nano-calcium carbonate particles, forming a denser structure and further improving the sealant's pressure resistance. Simultaneously, the hydroxyl groups on the titanium dioxide surface react with the coupling agent, enhancing interfacial bonding and reducing stress concentration. Moreover, the simultaneous presence of ultraviolet absorbers and light stabilizers synergistically delays aging. Based on this, the dispersed addition of titanium dioxide not only reflects ultraviolet light, forming a dual protective barrier with the ultraviolet absorber and significantly reducing the risk of resin chain breakage, but also, due to its high refractive index, substantially reduces light transmittance. This, in turn, synergistically with the light stabilizer to inhibit yellowing, significantly improving anti-aging capabilities. Therefore, this process not only effectively ensures the sealant's performance but also significantly improves production efficiency and reduces production costs.

[0033] Compared with the prior art, the present invention has the following advantages: 1. Environmental benefits: The MS sealant of this invention does not contain harmful substances such as formaldehyde and isocyanate, is solvent-free, and has a VOC emission level lower than the industry standard. It is harmless to the environment and the health of construction workers, and meets the environmental protection requirements of modern railway construction. At the same time, the MS sealant does not contain volatile solvents or easily migrating plasticizers, does not contain silicone oil or silicone resin, and will not attract dust from the air to cause pollution. It can keep the joints of ballastless track clean, which is conducive to the long-term maintenance and aesthetics of the track.

[0034] 2. Outstanding weather resistance and durability: The MS sealant of this invention has a stable molecular structure. Through the synergistic effect of titanium dioxide, ultraviolet absorbers and light stabilizers, it can effectively resist the erosion of natural factors such as ultraviolet rays, rain, and moisture. After 300 days of natural environmental aging, its mechanical properties retain more than 90%, which can reduce the maintenance frequency of ballastless tracks.

[0035] 3. Performance Advantages: According to GB / T13477, the mechanical test of this sealant showed a tensile strength of 1.23 MPa, an elongation at break of 824%, a 100% modulus of 0.149 MPa, an elastic recovery rate of 86.60%, and a surface drying time of 108 min. This means that the single-component MS sealant achieves an elastic recovery rate of over 85% and an elongation rate of over 800%, meeting the standard requirements for sealants used in ballastless track joints. This demonstrates excellent performance in terms of bond strength, tensile strength, elasticity, and curing speed, and can meet the needs of different application scenarios.

[0036] This method is simple to implement and has obvious advantages in sealant performance. Through the synergistic effect of multiple materials such as silane-modified polyether polymer, titanium dioxide and other specific components, it can prepare a single-component sealant with excellent performance in terms of bonding strength, tensile strength, elasticity and plasticity, weather resistance and curing speed, which solves the problem of insufficient performance of ballastless track caulking materials and is suitable for the stringent requirements of ballastless track caulking and sealing.

[0037] The sealant of the present invention will be further described below with reference to Examples 1 to 3: The preparation methods of sealants are mainly divided into cold methods and hot methods. This invention mainly uses the cold method to prepare the sealant. The sealant preparation revolves around the core process of "base material mixing → additive addition → dispersion and homogenization → degassing → packaging".

[0038] 1. Core equipment configuration: The cold preparation process is carried out entirely at room temperature, making it suitable for temperature-sensitive sealants. The core principle is to avoid high temperatures damaging the properties of the components. The equipment is based on "room temperature mixing + efficient degassing".

[0039] Mixing equipment: High-speed disperser, a mixing device for resins, fillers, and various functional additives, to achieve uniform mixing of high-viscosity materials at room temperature, with a maximum speed of 5000 rpm, and can precisely control the real-time speed of each feeding stage.

[0040] Degassing equipment: Low-temperature vacuum degassing tank, which further degasses the trace bubbles that remain after mixing at room temperature to ensure that the sealant is free of voids. The working temperature is ≤35℃, the vacuum degree is ≤-0.098MPa, and the degassing time is 10-20 minutes to avoid the volatilization of additives caused by high temperature.

[0041] Testing equipment: Equipped with a rheometer to test viscosity changes, an MTS tensile testing machine to test tensile strength, and a high and low temperature weathering test chamber to simulate ultraviolet radiation and high and low temperature aging, allowing for real-time monitoring of formulation performance under different environments.

[0042] 2. Example: Example 1: 100 parts of silane-modified polyether resin KANEKA MS POLYMER™ S327 and 85 parts of plasticizer diisodecyl phthalate were placed in a high-speed disperser and stirred at 500 rpm for 5 min. Then, 145 parts of nano-calcium carbonate, 45 parts of heavy calcium carbonate, and 15 parts of titanium dioxide were added in three batches. After mixing, the speed was gradually increased to 1000 rpm, 1500 rpm, and 2000 rpm, with each speed continuously stirred for 5 min to uniformly disperse the filler. Finally, 1 part of ultraviolet absorber bis(2,2,6,6-tetramethyl-4-piperidinyl) was added. Sebacic acid ester, 1 part of light stabilizer 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and 3.5 parts of thixotropic agent micro-powdered polyamide rheology modifier were stirred at 2700 rpm for 60 min. Every 5 min, 3.5 parts of dehydrating agent vinyltrimethoxysilane, 3.5 parts of coupling agent N-aminoethyl-3-aminopropylmethyldimethoxysilane, 10 parts of catalyst diisodecyl phthalate, 4 parts of catalyst 2-ethylhexanoate tin, and 2.4 parts of catalyst dodecylamine were added sequentially to obtain a mixed raw material. After stirring evenly, the mixed raw material was placed in a vacuum degassing machine, and the atmospheric pressure was maintained at -0.09 MPa to 0.1 MPa, and the rotation speed was 1000 rpm for 15 min to degas. After vacuum degassing treatment, a single-component sealant suitable for caulking of railway ballastless track joints was obtained.

[0043] Example 2: The sealant was prepared according to the method of Example 1, except that the amount of nano calcium carbonate was changed to 190 parts, the amount of heavy calcium carbonate was changed to 60 parts, and the plasticizer was changed from diisodecyl phthalate to polypropylene glycol 3000. Example 3: The sealant was prepared according to the method of Example 1, except that the amount of nano calcium carbonate was changed to 165 parts, the amount of heavy calcium carbonate was changed to 55 parts, and the plasticizer was changed from diisodecyl phthalate to polypropylene glycol 3000. Comparative Example 1: The sealant was prepared according to the method of Example 1, except that the amount of nano-calcium carbonate was changed to 190 parts, the amount of heavy calcium carbonate was changed to 60 parts, and the plasticizer was changed from diisodecyl phthalate to polypropylene glycol 3000. Comparative Example 2: The sealant was prepared according to the method of Example 1, except that the amount of nano-calcium carbonate was changed to 200 parts, the amount of heavy calcium carbonate was changed to 50 parts, and the plasticizer was changed from diisodecyl phthalate to polypropylene glycol 3000. Table 1 summarizes the composition and weight of each raw material in Examples 1-3 and Comparative Examples 1-2, as well as the performance test data of the prepared sealant.

[0044] Table 1: Formulation components and corresponding test data of Examples 1-3 and Comparative Examples 1-2 (Unit: parts) Based on the mechanical properties shown in the table above, it can be determined that Examples 1 and 2 fully meet the performance requirements of the sealant in the Q / CR 601-2017 standard "Sealing Materials for Railway Ballastless Track" in the five tested properties. They can be further optimized and put into use as examples suitable for sealing materials for railway ballastless track.

[0045] 3. Performance Testing: The performance of the sealants prepared in Examples 1-3 and Comparative Examples 1-2 was tested. Mechanical properties: Mechanical tests were conducted using an MTS tensile testing machine according to GB / T13477. Example 1 showed a tensile strength of 1.23 MPa, elongation at break of 824%, 100% modulus of 0.149 MPa, and 150% elastic recovery of 86.60%; Example 2 showed a tensile strength of 1.27 MPa, elongation at break of 1212%, 100% modulus of 0.202 MPa, and 150% elastic recovery of 85.10%; Example 3 showed a tensile strength of 1.22 MPa. The tensile strength of Comparative Example 1 was 1.12 MPa, with an elongation at break of 890%, a modulus of 0.150 MPa, and an elastic recovery rate of 84.40%. Comparative Example 2 had a tensile strength of 1.22 MPa, an elongation at break of 942%, a modulus of 0.143 MPa, and an elastic recovery rate of 83.60%. Meanwhile, in... Figures 2 to 5 The performance of the sealant prepared in this invention is intuitively demonstrated. The results effectively prove that the sealant prepared in Examples 1-3 above has significantly better performance than the sealant in the prior art, and can well meet the Q / CR 601-2017 standard "Sealing Material for Ballastless Track".

[0046] Curing performance: The surface drying time of Example 1 was 108 min, the surface drying time of Example 2 was 105 min, the surface drying time of Example 3 was 105 min, the surface drying time of Comparative Example 1 was 98 min, and the surface drying time of Comparative Example 2 was 92 min. All of these can effectively meet the needs of actual construction.

[0047] In summary, the single-component MS sealant and its preparation method for ballastless track caulking of the present invention have excellent performance, solve the problem of insufficient performance of ballastless track caulking sealing materials, and are suitable for the widespread application of ballastless track caulking sealing.

Claims

1. A one-component sealant suitable for use in the bedding of railway ballastless track, characterized in that, The raw materials of the single-component MS sealant include the following components in parts by weight: silane-modified polyether resin 90-120 parts, plasticizer 70-90 parts, nano calcium carbonate 120-190 parts, heavy calcium carbonate 20-80 parts, titanium white 10-30 parts, thixotropic agent 1-8 parts, ultraviolet absorber 1-5 parts, light stabilizer 1-5 parts, dehydrating agent 1-6 parts, coupling agent 1-6 parts, catalyst 10-30 parts; The nano calcium carbonate has a mesh number of 4000-5000 mesh; The heavy calcium carbonate has a mesh number of 200-800 mesh; The titanium white has a mesh number of 100-500 mesh.

2. The one-component sealant for railway ballastless track caulking according to claim 1, characterized in that, The silane-modified polyether resin 100 parts, plasticizer 85 parts, nano calcium carbonate 145 parts, heavy calcium carbonate 45 parts, titanium white 15 parts, thixotropic agent 3.5 parts, ultraviolet absorber 1 part, light stabilizer 1 part, dehydrating agent 3.5 parts, coupling agent 3.5 parts, catalyst 16.5 parts.

3. The one-component sealant for railway ballastless track caulking according to claim 2, characterized in that, The silane-modified polyether resin adopts KANEKA MS POLYMER™ S327 of Japan Zhonghua; the chemical structure of KANEKA MS POLYMER™ S327 is a polyether backbone, and the terminal is capped with a methoxysilane group; the pH value of KANEKA MS POLYMER™ S327 liquid resin is between 6.0-8.0, and the viscosity is between 25,000-43,000 mPa·s.

4. The one-component sealant for railway ballastless track caulking according to claim 3, characterized in that, The plasticizer is diisodecyl phthalate; the thixotropic agent is a micro-powdered polyamide rheological additive; the ultraviolet absorber is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate; the light stabilizer is 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole; the dehydrating agent is vinyltrimethoxysilane; the coupling agent is N-aminoethyl-3-aminopropylmethyldimethoxysilane; and the catalyst is diisodecyl phthalate, tin 2-ethylhexanoate and dodecyl primary amine.

5. A method for preparing a one-component sealant suitable for railway ballastless track caulking, characterized in that, The method comprises the following steps: Step one: put 90-120 parts of silane-modified polyether resin and 70-90 parts of plasticizer into a stirrer and stir at 500 rpm for 5 min; Step two: add 120-190 parts of nano calcium carbonate, 20-80 parts of heavy calcium carbonate and 10-30 parts of titanium white in three batches, mix and then increase the stirring speed to 1000 rpm, 1500 rpm and 2000 rpm in stages, and stir at each speed for 5 min to uniformly disperse the fillers; Step three: add 1-5 parts of ultraviolet absorber, 1-5 parts of light stabilizer and 1-8 parts of thixotropic agent, and stir at 2700 rpm for 60 min; Step four: add 1-6 parts of dehydrating agent, 1-6 parts of coupling agent and 1-6 parts of catalyst every 5 min to obtain a mixed raw material; Step five: after uniform stirring, put the mixed raw material into a vacuum defoaming machine, maintain the atmospheric pressure at -0.09 MPa to 0.1 MPa and the stirring speed at 1000 rpm for 15 min to perform vacuum bubble removal treatment, and obtain a single-component sealant suitable for railway ballastless track caulking.

6. The method for preparing a single-component sealant for railway ballastless track joint sealing according to claim 5, characterized in that, In step one, the silane-modified polyether resin is 100 parts, and the plasticizer is 85 parts; in step two, the nano calcium carbonate is added in three batches, 145 parts in total, the heavy calcium carbonate is 45 parts, and the titanium dioxide is 15 parts; in step three, the ultraviolet absorber is 1 part, the light stabilizer is 1 part, and the thixotropic agent is 3.5 parts; in step four, the dehydrating agent is 3.5 parts, the coupling agent is 3.5 parts, and the catalyst is 6.5 parts.

7. The method according to claim 5, wherein the single-component sealant for railway ballastless track joints is prepared by mixing the components (A) and (B) in a weight ratio of 1:1 to 1:2.

5. In step one, the silane-modified polyether resin is KANEKA MS POLYMER™ S327, and the plasticizer is diisodecyl phthalate; in step three, the ultraviolet absorber is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, the light stabilizer is 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and the thixotropic agent is a micro-powdered polyamide rheological additive; in step four, the dehydrating agent is vinyl trimethoxysilane, the coupling agent is N-aminoethyl-3-aminopropyl methyl dimethoxysilane, and the catalyst is diisodecyl phthalate, tin 2-ethylhexanoate, and dodecyl primary amine.

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