Rail transit water-based anticorrosive coating suitable for low temperature environment and preparation method thereof

Abstract

This invention discloses a water-based anti-corrosion coating for rail transit in low-temperature environments and its preparation method, belonging to the field of coating technology. The coating is composed of water-based epoxy-terminated amino-polyether modified epoxy resin composite resin, polyether-type water-based polyurethane elastomer (Tg≤-60℃), MP200 adhesion promoter, zinc phosphate-graphene composite pigment, modified nano-silica, and other components. It is prepared through pre-dispersion, resin mixing, curing system preparation, paint mixing and filtration. The ultra-low temperature toughening agent and composite resin synergistically improve flexibility (≤1mm) and adhesion (≤Grade 1) at -60℃; the graphene-zinc phosphate composite system forms a double anti-corrosion barrier, with salt spray resistance up to 1500h; the optimized curing process achieves drying within 12h at 20℃, with VOC ≤80g / L. This coating meets the Russian GOST standard and is suitable for anti-corrosion of rail transit in extreme low-temperature environments.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a water-based anti-corrosion coating for rail transit suitable for low-temperature environments (-40℃ to -60℃) and its preparation method. Background Technology

[0002] Extreme low-temperature environments (winter temperatures often below -40°C) pose stringent challenges to the performance of anti-corrosion coatings. Existing water-based anti-corrosion coatings have the following key drawbacks:

[0003] 1. Insufficient low-temperature performance: The coating is prone to embrittlement below -30℃, and its flexibility is significantly reduced (bending test >3mm), resulting in cracking and peeling; the low-temperature adhesion decays to level 2 or below (GOST15140 standard), which cannot meet the requirements for long-term use;

[0004] 2. Poor synergy between corrosion resistance and weather resistance: In salt spray, sulfur dioxide and alternating hot and cold environments, the corrosion resistance life of the coating is less than 1000h, which is far below the mandatory requirement of 720h resistance to damp heat and sulfur dioxide for Russian rail transit (GOST9.401).

[0005] 3. Poor construction adaptability: The curing time at low temperatures exceeds 24 hours (GOST 19007 standard requires ≤12 hours@20℃), and the dilution stability is poor, which affects construction efficiency.

[0006] While existing low-temperature coatings from Germany and Japan offer superior performance, they rely on solvent-based systems (VOC > 300 g / L), failing to meet environmental protection requirements. Therefore, developing water-based anti-corrosion coatings that combine ultra-low temperature toughness, long-lasting corrosion resistance, environmental friendliness, and rapid curing properties has become an urgent technical challenge. Summary of the Invention

[0007] Purpose of the Invention: This invention aims to address the performance deficiencies of existing coatings in extreme low-temperature environments. Through formulation innovation and process optimization, the following objectives are achieved:

[0008] 1. Maintains excellent adhesion (≤1 grade), flexibility (≤1mm) and impact resistance (≥50cm) at temperatures ranging from -40℃ to -60℃.

[0009] 2. Its salt spray resistance exceeds 1300 hours and its sulfur dioxide corrosion resistance exceeds 1500 hours, far exceeding the GOST standard;

[0010] 3. Curing time ≤ 12h@20℃, VOC ≤ 80g / L, meeting environmental protection and construction requirements.

[0011] Technical Solution: A water-based anti-corrosion coating for rail transit in low-temperature environments, comprising, by weight: 30-45 parts of water-based epoxy-terminated amino polyether modified epoxy resin composite resin, 5-10 parts of low-temperature toughening agent, 1.5-3 parts of adhesion promoter, 10-15 parts of composite anti-corrosion pigment, 5-8 parts of functional filler, 8-12 parts of water-based curing agent, and additives: 0.3-0.8 parts of defoamer (BYK-024, BYK Chemical), 0.5-1.2 parts of dispersant (Dispex Ultra PA 4575, BASF), and 10-20 parts of deionized water.

[0012] Preferably, the waterborne epoxy-amino-terminated polyether modified epoxy resin composite resin has an epoxy equivalent of 220-320 g / eq, and the amino-terminated polyether modified epoxy resin accounts for 25-35% of the total mass of the composite resin.

[0013] Preferably, the low-temperature toughening agent is a polyether-type waterborne polyurethane elastomer with a number average molecular weight of 10,000-14,000 and a glass transition temperature T. g ≤-60℃, solid content 35-45%.

[0014] Preferably, the adhesion promoter is a silane coupling agent MP200.

[0015] Preferably, the composite anti-corrosion pigment is a zinc phosphate-graphene composite system (graphene content 3-5%), where the graphene sheets form a physical barrier.

[0016] Preferably, the functional filler is nano-silica (particle size 20-50nm), surface-modified with octyltriethoxysilane. The modification process is as follows: industrial-grade nano-silica powder with an initial particle size D50 ≤ 100nm is passed through a 200-mesh filter to initially remove large particulate impurities, and the sieved material is collected; the sieved nano-silica is mixed with ethanol to prepare a slurry with a 20% solid content, pumped into a sand mill, using 0.1mm zirconia beads as the grinding medium, with a bead-to-material ratio of 8:1, and grinding is stopped when D50 reaches 20-50nm; the ground nano-silica ethanol slurry is transferred to an ultrasonic tank and ultrasonicated at room temperature for 30 minutes. The material is transferred to a stirring container, heated to 80℃, and octyltriethoxysilane solution is added dropwise with stirring; after the addition is complete, the reaction is maintained at 80℃ for 3 hours. The mixture is centrifuged, the filter cake is collected, and washed three times with anhydrous ethanol; the washed filter cake is vacuum dried to obtain modified nano-silica.

[0017] Preferably, the aqueous curing agent is a modified aliphatic amine (Evonik, Germany, Anquamine 419) with an active hydrogen equivalent of 120-150 g / eq.

[0018] The preparation methods of water-based anti-corrosion coatings include:

[0019] (1) Dispersion (grinding): Add deionized water, dispersant and defoamer to the dispersion vessel and stir at 800-1000 rpm for 10 min; add composite anticorrosive pigment and functional filler, heat to 50-60℃, disperse at high speed at 1500-2000 rpm for 30 min and then grind in a sand mill, controlling the pigment particle size ≤30μm;

[0020] (2) Resin mixing: Add the waterborne epoxy-terminated amino polyether modified epoxy resin composite resin to the system of step (1), stir at 600-800 rpm for 20 min; add low-temperature toughening agent (polyether-type waterborne polyurethane elastomer) and adhesion promoter, continue stirring for 30 min to form a uniform resin-pigment system, which is component A; the polyether-type waterborne polyurethane elastomer is uniformly dispersed in the system as nano-sized particles (particle size ≤ 500 nm) by high-speed stirring to form a physical blend structure of "resin continuous phase + elastomer dispersed phase". The synthesis method of waterborne epoxy-terminated amino polyether modified epoxy resin composite resin is as follows: add the basic epoxy emulsion (epoxy equivalent (EEW) of 220-320 g / eq, solid content of 50%) to the reactor, start stirring (400 rpm), and slowly heat to 65℃. The terminal amine polyether (Jeffamine D-2000, molecular weight approximately 2000 g / mol, solid content 100%) was slowly and evenly added dropwise to the reaction vessel using a dropping funnel. The dropping rate was controlled to stabilize the reaction temperature at 75℃. The reaction was maintained at 75℃ for 2.5 hours. During this period, the amine value of the system was monitored to determine the reaction progress. The reaction was considered complete when the consumption of epoxy groups reached near the theoretically calculated value. After the reaction was complete, the system was cooled to below 40℃, and then the product was discharged and packaged to obtain the final waterborne epoxy-terminated amine polyether modified epoxy resin composite resin, which accounted for 25-35% of the total mass of the composite resin. The chemical reaction formulas involved are as follows:

[0021] ;

[0022] (3) Preparation of curing system: Mix the water-based curing agent with (anti-flash rust additive, water, etc.) in a separate container and stir at 500 rpm for 10 min to obtain component B;

[0023] Before using the coating, it needs to be mixed and filtered: Slowly add component B from step (3) to component A from step (2), stir at 500-600 rpm for 15 minutes, and adjust the viscosity to the coating requirements; filter through a 100-mesh filter to obtain the finished coating; wherein the amino group (-NH2) of the modified aliphatic amine (Evonik, Anquamine 419) undergoes a ring-opening reaction with the epoxy group of the waterborne epoxy-terminated amino polyether modified epoxy resin composite resin, and the reaction formula is as follows:

[0024] .

[0025] Beneficial effects:

[0026] Breakthrough in ultra-low temperature performance: By combining a polyether-type waterborne polyurethane elastomer with a Tg≤-60℃ (physical dispersion toughening) with a waterborne epoxy-terminated amino polyether modified epoxy resin composite resin (introduction of flexible segments), it still maintains Grade 1 adhesion and ≤1mm flexibility at -60℃, solving the problem of low-temperature embrittlement of traditional coatings.

[0027] Long-lasting corrosion protection innovation: The graphene-zinc phosphate composite system forms a dual protection of "physical shielding + chemical corrosion inhibition", with salt spray resistance of more than 1300 hours, far exceeding the GOST 720-hour standard;

[0028] Balancing construction and environmental protection: Low-temperature curing technology enables drying within 12 hours at 20℃, with VOC ≤ 80g / L, meeting Russian environmental protection requirements and reducing construction energy consumption. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1:

[0031] Preparation of modified nano-silica (50nm): Industrial-grade nano-silica powder with an initial particle size D50 ≤ 100nm was initially filtered through a 200-mesh screen to remove large particle impurities, and the sieved material was collected. The sieved nano-silica was mixed with ethanol to prepare a slurry with a 20% solid content, which was pumped into a sand mill. 0.1mm zirconia beads were used as the grinding medium, with a bead-to-particle ratio of 8:1, and grinding was carried out at 1000rpm. Grinding was stopped when the D50 reached 50nm. The ground nano-silica ethanol slurry was transferred into an ultrasonic tank, with the probe inserted to a depth of 1 / 3 of the slurry. Ultrasonication was carried out at room temperature. The ultrasonic dispersion was carried out for 30 minutes; at the same time, a low-speed stirrer (200 rpm) was turned on to avoid local overheating of the ultrasonication and re-agglomeration of the particles; the ultrasonically dispersed nano-silica ethanol slurry (solid content 20%) was added to the stirring tank, the temperature was raised to 80℃, and the stirrer was turned on at 800 rpm; octyltriethoxysilane solution was added dropwise, and after the addition was completed, the reaction was kept at 80℃ for 3 hours; the mixture was centrifuged and filtered, the bottom precipitate was collected, the filtrate was discarded, and the filter cake was washed three times with anhydrous ethanol; the washed filter cake was vacuum dried for 3 hours (100℃, -0.08 MPa) to obtain modified nano-silica.

[0032] (1) Pre-dispersion: Add 20 parts of deionized water, 1.2 parts of dispersant (Dispex Ultra PA 4575, BASF) and 0.8 parts of defoamer (BYK-024, BYK Chemical) to the dispersion vessel and stir at 1000 rpm for 10 min; add 15 parts of zinc phosphate-graphene pigment (5% graphene) and 8 parts of modified nano silica (50 nm), heat to 60℃, disperse at 2000 rpm for 30 min and then grind in a mill to control the pigment particle size ≤22 μm.

[0033] (2) Resin Mixing: The base epoxy emulsion (epoxy equivalent (EEW) of 320 g / eq, solid content of 50%) was added to the reactor, and stirring was started (400 rpm), and the temperature was slowly raised to 65°C. The terminal amino polyether (Jeffamine D-2000, molecular weight of approximately 2000 g / mol, solid content of 100%) was slowly and evenly added to the reactor through a dropping funnel. The dropping rate was controlled to stabilize the reaction temperature at 75°C. The reaction was maintained at 75°C for 2.5 hours. During this period, the reaction progress was judged by monitoring the amine value of the system. When the consumption of epoxy groups reached near the theoretical calculation value, the reaction was considered complete. After the reaction was completed, the system was cooled to below 40°C, and the product was discharged and packaged to obtain the final waterborne epoxy-terminated amino polyether modified epoxy resin composite resin, which accounted for 35% of the total mass of the composite resin. Add 45 parts of waterborne epoxy-amino-terminated polyether modified epoxy resin composite resin (epoxy equivalent 320g / eq, amino-terminated polyether modified epoxy content 35%) to the system in step (1), and stir at 700rpm for 20min; add 10 parts of polyether-type waterborne polyurethane elastomer (molecular weight 14000, Tg=-62℃, solid content 45%) and 3 parts of adhesion promoter MP200, and continue stirring for 30min to form a uniform resin-pigment system, which is component A.

[0034] (3) Preparation of curing system: Mix 12 parts of modified aliphatic amine (Evonik, Germany, Anquamine 419) in a separate container and stir at 500 rpm for 10 min to form component B.

[0035] (4) Paint preparation and filtration: Components A and B are stored separately. Before using the paint, slowly add the curing system of step (3) to the mixture of step (2), stir at 550 rpm for 15 min, and adjust the viscosity to the coating requirements; filter through a 100-mesh filter to obtain the finished paint.

[0036] Example 2:

[0037] Preparation of modified nano-silica (20nm): Industrial-grade nano-silica powder with an initial particle size D50≤100nm was passed through a 200-mesh filter to remove large particulate impurities. After sieving, the sieved material was collected. The sieved nano-silica was mixed with ethanol to prepare a slurry with a solid content of 20%, which was then pumped into a sand mill. 0.1 mm zirconia beads were used as the grinding medium at a bead-to-material ratio of 8:1, and grinding was carried out at 1000 rpm until the D50 reached 20 nm. The ground nano-silica ethanol slurry was then transferred to an ultrasonic tank, with the probe inserted to 1 / 3 of the slurry depth. The slurry was ultrasonically treated for 30 min at room temperature. Simultaneously, low-speed stirring (200 rpm) was started to prevent local overheating during ultrasonic treatment, which could lead to particle re-agglomeration. The ultrasonically dispersed nano-silica ethanol slurry (20% solid content) was added to a mixing tank, heated to 80 °C, and stirred at 800 rpm. Octyltriethoxysilane solution was added dropwise, and the mixture was kept at 80 °C for 3 h after the addition was complete. The mixture was centrifuged and filtered, the filter cake was collected, the filtrate was discarded, and the filter cake was washed three times with anhydrous ethanol. The washed filter cake was then vacuum dried for 3 h (100 °C, -0.08 MPa) to obtain modified nano-silica.

[0038] (1) Pre-dispersion: Add 10 parts of deionized water, 0.5 parts of dispersant (Dispex Ultra PA 4575, BASF) and 0.3 parts of defoamer (BYK-024, BYK Chemical) to the dispersion vessel and stir at 1000 rpm for 10 min; add 10 parts of zinc phosphate-graphene pigment (graphene 3%) and 5 parts of modified nano silica (20 nm), heat to 50℃, disperse at 1500 rpm for 30 min and then grind in a mill to control the particle size of the material to ≤28 μm.

[0039] (2) Resin Mixing: The base epoxy emulsion (epoxy equivalent (EEW) of 220 g / eq, solid content of 50%) was added to the reactor, and stirring was started (400 rpm), and the temperature was slowly raised to 65°C. The terminal amino polyether (Jeffamine D-2000, molecular weight of approximately 2000 g / mol, solid content of 100%) was slowly and evenly added to the reactor through a dropping funnel. The dropping rate was controlled to stabilize the reaction temperature at 75°C. The reaction was maintained at 75°C for 2.5 hours. During this period, the reaction progress was judged by monitoring the amine value of the system. When the consumption of epoxy groups reached near the theoretical calculation value, the reaction was considered complete. After the reaction was completed, the system was cooled to below 40°C, and the product was discharged and packaged to obtain the final waterborne epoxy-terminated amino polyether modified epoxy resin composite resin, which accounted for 25% of the total mass of the composite resin. Add 30 parts of waterborne epoxy-terminated amino polyether modified epoxy resin composite resin (epoxy equivalent 220g / eq, amino polyether modified epoxy content 25%) to the system in step (1), and stir at 600rpm for 20min; add 10 parts of polyether-type waterborne polyurethane elastomer (molecular weight 10000, Tg=-60℃, solid content 35%) and 3 parts of pretreated adhesion promoter MP200, and continue stirring for 30min to form a uniform resin-pigment system, which is component A.

[0040] (3) Preparation of curing system: Mix 12 parts of modified aliphatic amine (Evonik, Germany, Anquamine 419) in a separate container and stir at 500 rpm for 10 min. This is component B.

[0041] (4) Paint mixing and filtration: Before using the paint, slowly add the curing system of step (3) to the mixture of step (2), stir at 500 rpm for 15 minutes, and adjust the viscosity to the coating requirements; filter through a 100-mesh filter to obtain the finished paint.

[0042] Example 3:

[0043] Preparation of modified nano-silica (30nm): Industrial-grade nano-silica powder with an initial particle size D50 ≤ 100nm was initially removed by passing it through a 200-mesh filter to remove large particle impurities. The sieved material was collected. The sieved nano-silica was mixed with ethanol to prepare a slurry with a solid content of 20%, which was then pumped into a sand mill. 0.1mm zirconia beads were used as the grinding medium at a bead-to-powder ratio of 8:1, and grinding was carried out at 1000rpm until the D50 reached 30nm. The ground nano-silica ethanol slurry was then transferred to an ultrasonic tank, with the probe inserted to 1 / 3 of the slurry depth. Ultrasonication was carried out at room temperature for 30min, while low-speed stirring (200rpm) was started simultaneously to avoid local overheating during ultrasonication that could cause particle re-agglomeration. The ultrasonically dispersed nano-silica ethanol slurry (20% solid content) was added to a mixing tank, heated to 80℃, and stirred at 800rpm. Octyltriethoxysilane solution was added dropwise. After the addition was completed, the mixture was kept at 80℃ for 3h. Centrifuge and filter, collect the filter cake, discard the filtrate, and wash the filter cake three times with anhydrous ethanol; vacuum dry the washed filter cake for 3 hours (100℃, -0.08Mpa) to obtain modified nano-silica.

[0044] (1) Pre-dispersion: Add 15 parts of deionized water, 0.8 parts of dispersant (Dispex Ultra PA 4575, BASF) and 0.5 parts of defoamer (BYK-024, BYK Chemical) to the dispersion vessel and stir at 1000 rpm for 10 min; add 12 parts of zinc phosphate-graphene pigment (graphene 4%) and 6 parts of modified nano silica (30 nm), heat to 55℃, disperse at 1800 rpm for 30 min, and control the pigment particle size ≤25 μm.

[0045] (2) Resin Mixing: The base epoxy emulsion (epoxy equivalent (EEW) of 280 g / eq, solid content of 50%) was added to the reactor, and stirring was started (400 rpm), and the temperature was slowly raised to 65°C. The terminal amino polyether (Jeffamine D-2000, molecular weight of approximately 2000 g / mol, solid content of 100%) was slowly and evenly added to the reactor through a dropping funnel. The dropping rate was controlled to stabilize the reaction temperature at 75°C. The reaction was maintained at 75°C for 2.5 hours. During this period, the reaction progress was judged by monitoring the amine value of the system. When the consumption of epoxy groups reached near the theoretical calculation value, the reaction was considered complete. After the reaction was completed, the system was cooled to below 40°C, and the product was discharged and packaged to obtain the final waterborne epoxy-terminated amino polyether modified epoxy resin composite resin with the terminal amino polyether modified epoxy resin accounting for 30% of the total mass of the composite resin. Add 35 parts of waterborne epoxy-amino-terminated polyether modified epoxy resin composite resin (epoxy equivalent 280g / eq, amino-terminated polyether modified epoxy content 30%) to the system in step (1), and stir at 800rpm for 20min; add 10 parts of polyether-type waterborne polyurethane elastomer (molecular weight 12000, Tg=-61℃, solid content 40%) and 3 parts of pretreated adhesion promoter MP200, and continue stirring for 30min to form a uniform resin-pigment system, which is component A.

[0046] (3) Preparation of curing system: Mix 10 parts of modified aliphatic amine (Evonik, Germany, Anquamine 419) in a separate container and stir at 500 rpm for 10 min. This is component B.

[0047] (4) Paint mixing and filtration: Before using the paint, slowly add the curing system of step (3) to the mixture of step (2), stir at 600 rpm for 15 minutes, and adjust the viscosity to the coating requirements; filter through a 100-mesh filter to obtain the finished paint.

[0048] Comparative Example 1:

[0049] (1) Pre-dispersion: Add 20 parts of deionized water, 1.2 parts of dispersant (Dispex Ultra PA 4575, BASF) and 0.8 parts of defoamer (BYK-024, BYK Chemical) to the dispersion vessel and stir at 1000 rpm for 10 min; add 15 parts of zinc phosphate and 8 parts of modified nano silica (50 nm), heat to 60℃, disperse at 2000 rpm for 30 min, and control the particle size of the material to ≤22 μm.

[0050] (2) Resin Mixing: The base epoxy emulsion (epoxy equivalent (EEW) of 320 g / eq, solid content of 50%) was added to the reactor, and stirring was started (400 rpm), and the temperature was slowly raised to 65°C. The terminal amino polyether (Jeffamine D-2000, molecular weight of approximately 2000 g / mol, solid content of 100%) was slowly and evenly added to the reactor through a dropping funnel. The dropping rate was controlled to stabilize the reaction temperature at 75°C. The reaction was maintained at 75°C for 2.5 hours. During this period, the reaction progress was judged by monitoring the amine value of the system. When the consumption of epoxy groups reached near the theoretical calculation value, the reaction was considered complete. After the reaction was completed, the system was cooled to below 40°C, and the product was discharged and packaged to obtain the final waterborne epoxy-terminated amino polyether modified epoxy resin composite resin, which accounted for 35% of the total mass of the composite resin. Add 45 parts of waterborne epoxy-amino-terminated polyether modified epoxy resin composite resin (epoxy equivalent 320 g / eq, amino-terminated polyether modified epoxy content 35%) to the system in step (1), and stir at 700 rpm for 20 min; add 10 parts of polyether-type waterborne polyurethane elastomer (molecular weight 14000, Tg=-62℃, solid content 45%) and 3 parts of pretreated adhesion promoter MP200, and continue stirring for 30 min to form a uniform resin-pigment system, which is component A.

[0051] (3) Preparation of curing system: Mix 12 parts of modified aliphatic amine (Evonik, Germany, Anquamine 419) in a separate container and stir at 500 rpm for 10 min. This is component B.

[0052] (4) Paint mixing and filtration: Slowly add the curing system of step (3) to the mixture of step (2), stir at 550 rpm for 15 min, adjust the viscosity to the coating requirements; filter through a 100-mesh filter to obtain the finished coating.

[0053] Comparative Example 2:

[0054] (1) Pre-dispersion: Add 20 parts of deionized water, 1.2 parts of dispersant (Dispex Ultra PA 4575, BASF) and 0.8 parts of defoamer (BYK-024, BYK Chemical) to the dispersion vessel and stir at 1000 rpm for 10 min; add 15 parts of zinc phosphate and 8 parts of modified nano silica (50 nm), heat to 60℃, disperse at 2000 rpm for 30 min, and control the pigment particle size ≤22 μm.

[0055] (2) Resin Mixing: The base epoxy emulsion (epoxy equivalent (EEW) of 320 g / eq, solid content of 50%) was added to the reactor, and stirring was started (400 rpm), and the temperature was slowly raised to 65°C. The terminal amino polyether (Jeffamine D-2000, molecular weight of approximately 2000 g / mol, solid content of 100%) was slowly and evenly added to the reactor through a dropping funnel. The dropping rate was controlled to stabilize the reaction temperature at 75°C. The reaction was maintained at 75°C for 2.5 hours. During this period, the reaction progress was judged by monitoring the amine value of the system. When the consumption of epoxy groups reached near the theoretical calculation value, the reaction was considered complete. After the reaction was completed, the system was cooled to below 40°C, and the product was discharged and packaged to obtain the final waterborne epoxy-terminated amino polyether modified epoxy resin composite resin, which accounted for 35% of the total mass of the composite resin. Add 45 parts of waterborne epoxy-terminated polyether modified epoxy resin composite resin (epoxy equivalent 320g / eq, end-amine polyether modified epoxy content 35%) to the system in step (1), and stir at 700rpm for 20min; add 10 parts of ordinary waterborne polyurethane elastomer (Tg=-30℃, molecular weight 8000, solid content 30%) and 3 parts of pretreated adhesion promoter MP200, and continue stirring for 30min to form a uniform resin-pigment system.

[0056] (3) Preparation of curing system: Mix 12 parts of modified aliphatic amine (Evonik, Germany, Anquamine 419) in a separate container and stir at 500 rpm for 10 min for later use.

[0057] (4) Paint mixing and filtration: Slowly add the curing system of step (3) to the mixture of step (2), stir at 550 rpm for 15 min, adjust the viscosity to the coating requirements; filter through a 100-mesh filter to obtain the finished coating.

[0058] Low-temperature adhesion test (-60℃):

[0059] Instruments: Low temperature constant temperature chamber (temperature control accuracy ±1℃), cross-cut tester (1mm grid), transparent tape (adhesive strength ≥3N / 10mm), magnifying glass (10x).

[0060] Test parameters: Sample: Low carbon steel test plate (150mm×70mm×1mm), coated and dried at 20℃ for 168h, placed in a -60℃ low temperature chamber for 2h; tested at room temperature (20±2℃).

[0061] Results analysis: According to the GOST 15140 standard, 6×6 1mm grids were drawn using a grid cutter. 2 The grid (depth to the substrate) is applied and then quickly peeled off. The peeling is observed with a magnifying glass: Level 1 (Gt0) is no peeling, and Level 2 (Gt1) is ≤5% peeling of a single cell. The rating results are recorded.

[0062] Flexibility (-40℃ bending) test:

[0063] Instruments: Low temperature constant temperature chamber (temperature control accuracy ±1℃), bending test machine (shaft diameter 0.5-5mm), vernier caliper (accuracy 0.01mm).

[0064] Test parameters: Sample: Low carbon steel test plate (150mm×70mm×1mm), coated and dried at 20℃ for 168h, placed in a -60℃ low temperature chamber for 2h; bending test was performed at -40℃; bending conditions: 180° bending, speed 30mm / min, using 1mm, 2mm, and 3mm shafts in sequence.

[0065] Results analysis: According to the GOST 6806 standard, observe whether the coating at the bend has cracks, and record the minimum diameter of the shaft without cracks (≤1mm is acceptable).

[0066] Impact resistance test (-40℃):

[0067] Instruments: Low temperature constant temperature chamber (temperature control accuracy ±1℃), impact testing machine (punch diameter 12.7mm, weight 1kg).

[0068] Test parameters: Sample: Low carbon steel test plate (150mm×70mm×1mm), dried at 20℃ for 168h after coating, and placed in a -60℃ low temperature chamber for 2h; impact test was carried out at -40℃; Impact conditions: a heavy hammer was dropped freely from a height of 50cm and impacted the coating surface (the punch was perpendicular to the coating).

[0069] Results analysis: According to the GOST R53007 standard, observe whether the coating peels off or cracks after impact. No damage at a height of ≥50cm is considered qualified. Record the maximum height without damage.

[0070] Salt spray resistance test:

[0071] Instruments: Salt spray test chamber (temperature control accuracy ±2℃, spray pressure 0.07-0.17MPa), pH meter (accuracy ±0.1).

[0072] Test parameters: Sample: Phosphate-treated test plate, dried at 20℃ for 7 days after coating (complete curing); Salt spray conditions: 3% NaCl solution (pH=6.5-7.2), temperature 35±2℃, continuous spraying for 1500h.

[0073] Results analysis: In accordance with the GOST 9.403 standard, observations were conducted every 24 hours, and the time when the coating showed signs of rust, blistering, or peeling was recorded.

[0074] Sulfur dioxide resistance (5mg / m³) 3 )test:

[0075] Instruments: Humidity chamber (temperature control ±2℃, humidity control ±3%), SO2 chamber (concentration accuracy ±1mg / m³) 3 ), low temperature chamber (temperature control ±3℃), climate chamber (spray function).

[0076] Test parameters: Sample: Phosphate-treated test plate, dried at 20℃ for 7 days after coating (complete curing);

[0077] Cyclic conditions (24h / cycle, 67 cycles in total):

[0078] - Humidity chamber: 40±2℃, 97±3%RH, 2h;

[0079] SO2 chamber: 5±1mg / m³ 3 SO2, 40±2℃, 97±3%RH, 2h;

[0080] -Cryogenic chamber: -30±3℃, 6h;

[0081] - Climate chamber: 60±3℃, 3min spray + 17min stop spray, 5h;

[0082] -Low-temperature chamber: -60±3℃, 3h;

[0083] - Room temperature: 15-30℃, ≤80%RH, 6h.

[0084] Results analysis: In accordance with the GOST 9.403 standard, observations were conducted every 24 hours, and the time when the coating showed signs of rust, blistering, or peeling was recorded.

[0085] Drying time (20℃) test:

[0086] Instruments: constant temperature chamber (temperature control 20±1℃), finger touch test tool (degreased cotton).

[0087] Test parameters: Sample: Dry film thickness of 40-60μm after coating; Test interval: Check every 2 hours until level 3 dryness is achieved.

[0088] Results analysis: According to the GOST19007 standard, the finger touch test was used to determine that Level 3 dryness is characterized by no traces when touched and no deformation when lightly pressed. The time to reach this level was recorded (≤12h is considered qualified).

[0089] VOC content test:

[0090] Instruments: Gas chromatograph (FID detector), analytical balance (accuracy 0.1 mg), constant temperature oven (105±2℃).

[0091] Test parameters: Specimen: Weigh 5 - 10 g of the coating and add an appropriate amount of diluent (dilution ratio in accordance with GOST8784); Test conditions: Chromatographic column DB-5 (30 m × 0.32 mm), column temperature 50 - 250 °C (programmed temperature rise), carrier gas N2 (1 mL / min).

[0092] Result analysis: Referring to the GB30981-2020 standard, the total amount of volatile organic compounds is determined by gas chromatography, and the VOC value is calculated (≤80 g / L is qualified). The test results are summarized in Table 1.

[0093] Table 1 Performance comparison and analysis table

[0094]

[0095] Examples 1 - 3, through the synergistic anti-corrosion of graphene and zinc phosphate and the molecular design of ultra-low temperature toughening agents, have significantly better adhesion, flexibility and corrosion resistance at extremely low temperatures than the comparative examples. Among them, Example 1 has the best comprehensive performance due to the increase in graphene content and the optimization of the toughening agent molecular weight. In a low-temperature environment, the flexibility performance is improved from 3 mm to 1 mm, and the impact resistance performance is improved from 35 cm to 60 cm. At the same time, it has excellent anti-corrosion performance, with the salt spray resistance performance test reaching up to 1500 h and the sulfur dioxide resistance performance reaching 1600 h, which is doubled at most compared with the comparative examples, and the shortest drying time is 9 h, fully meeting the requirements of GOST 19007.

[0096] The above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various examples of the present invention.

Claims

1. A water-based anticorrosive paint for rail transportation in a low temperature environment, characterized by, The composition by weight includes: 30-45 parts of waterborne epoxy-terminated polyether modified epoxy resin composite resin, 5-10 parts of low-temperature toughening agent, 1.5-3 parts of adhesion promoter, 10-15 parts of composite anti-corrosion pigment, 5-8 parts of functional filler, 8-12 parts of waterborne curing agent, 0.8-2.0 parts of additives, and 10-20 parts of deionized water; wherein the additives include: 0.3-0.8 parts of defoamer and 0.5-1.2 parts of dispersant; the epoxy equivalent of the waterborne epoxy-terminated polyether modified epoxy resin composite resin is 220-320 g / eq, and the amine-terminated polyether modified epoxy resin accounts for 25-35% of the total mass of the composite resin; The low-temperature toughening agent is a polyether-type waterborne polyurethane elastomer with a number-average molecular weight of 10,000-14,000, a glass transition temperature Tg ≤ -60℃, and a solid content of 35-45%. The composite anti-corrosion pigment is a zinc phosphate-graphene composite pigment, wherein the mass fraction of graphene is 3-5%.

2. The water-based anticorrosive paint for rail transportation in a low temperature environment according to claim 1, characterized in that, The adhesion promoter is silane coupling agent MP200. 3.The rail transit water-based anticorrosive paint suitable for low-temperature environment according to claim 1, characterized in that, The functional filler is nano-silica modified with octyltriethoxysilane, with a particle size D50 of 20-50 nm. The modification process is as follows: industrial-grade nano-silica powder with an initial particle size D50 ≤ 100 nm is passed through a 200-mesh filter to initially remove large particulate impurities, and the sieved material is collected; the sieved nano-silica is mixed with ethanol to prepare a slurry with a solid content of 20%, which is pumped into a sand mill using 0.1 mm zirconia beads as the grinding medium at a bead-to-material ratio of 8:1, and grinding is stopped when the D50 reaches 20-50 nm; the ground nano-silica ethanol slurry is transferred to an ultrasonic tank and ultrasonicated at room temperature for 30 min; the material is transferred to a stirring container, heated to 80 °C, and octyltriethoxysilane solution is added dropwise with stirring; after the addition is completed, the reaction is kept at 80 °C for 3 h; the filter cake is collected by centrifugation and washed three times with anhydrous ethanol; the washed filter cake is vacuum dried to obtain modified nano-silica. 4.The rail transit water-based anticorrosive paint suitable for low-temperature environment according to claim 1, characterized in that, The water-based curing agent is a modified aliphatic amine with an active hydrogen equivalent of 120-150 g / eq.

5. A method for preparing a water-based anticorrosive coating for rail transportation in low temperature environments according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Pre-dispersion: Add deionized water, dispersant and defoamer to the dispersion vessel and stir at 800-1000 rpm for 10 min; add composite anticorrosive pigment and functional filler, heat to 50-60℃, disperse at high speed at 1500-2000 rpm for 30 min and then grind in a grinder, controlling the particle size of the material to ≤30μm; (2) Resin mixing: Add the waterborne epoxy-terminated amino polyether modified epoxy resin composite resin to the system of step (1), stir at 600-800 rpm for 20 min; add low-temperature toughening agent and adhesion promoter, continue stirring for 30 min to form a uniform resin-pigment system, which is component A; the polyether-type waterborne polyurethane elastomer is uniformly dispersed in the system with nano-sized particles with a particle size ≤500 nm by high-speed stirring to form a physical blend structure of "resin continuous phase + elastomer dispersed phase"; wherein the synthesis method of waterborne epoxy-terminated amino polyether modified epoxy resin composite resin is: add the base epoxy emulsion to The mixture is placed in a reaction vessel, stirred, and slowly heated to 65°C. The terminal amino polyether is slowly and evenly added to the reaction vessel through a dropping funnel. The dropping rate is controlled to stabilize the reaction temperature at 75°C. The reaction is maintained at 75°C for 2.5 hours. During this period, the reaction progress is judged by monitoring the amine value of the system. When the consumption of epoxy groups reaches near the theoretical calculation value, the reaction is considered complete. After the reaction is completed, the system is cooled to below 40°C, and then the product is discharged and packaged to obtain the final waterborne epoxy-terminated amino polyether modified epoxy resin composite resin, which accounts for 25-35% of the total mass of the composite resin. (3) Preparation of curing system: Mix the water-based curing agent in a separate container and stir at 500 rpm for 10 min to obtain component B; keep component A and component B prepared in the above steps separately to prepare a water-based anti-corrosion coating for rail transit in low temperature environment. During use, the paint preparation method is as follows: slowly add component B to component A, stir at 500-600 rpm for 15 minutes, adjust the viscosity to the coating requirements; filter through a 100-mesh filter to obtain the finished paint.

6. The method of preparing a rail transit waterborne anticorrosive coating according to claim 5, characterized in that, The coating in step (3) is prepared into a coating film using a wet film preparation device.

7. Use of a waterborne anticorrosive coating for rail transport in low temperature environments according to any of claims 1 to 4, characterized in that, For corrosion protection of rail transit vehicles and facilities in environments ranging from -40℃ to -60℃, the following performance requirements must be met: (1) Adhesion: ≤ Grade 1 at -60℃; (2) Flexibility: ≤1mm when bent at -40℃; (3) Impact resistance: ≥50cm at -40℃; (4) Salt spray resistance ≥1300h, sulfur dioxide resistance ≥1500h; (5) VOC content ≤ 80g / L.

Images