A drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments, its preparation method and application.

Abstract

This invention relates to a drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments, its preparation method, and its application. The coating comprises component A and component B, with the following mass percentages of raw materials: Component A: epoxy resin 15.0–25.0%; modified resin 15.0–25.0%; reactive diluent 8.0–15.0%; TDI adduct 0.5–2.0%; leveling agent 0.2–0.5%; defoamer 0.2–0.5%; dispersant 0.4–0.8%; bentonite 0.2–1.0%; zinc phosphate 5.0–15.0%; silicon carbide 3.0–15.0%; iron oxide red 5.0–10.0%; kaolin 5.0–10.0%; silica fume 5.3–15.2%; Component B: modified amine 99.0–99.8%; thixotropic synergist 0.2–1.0%. Compared with the prior art, the coating of the present invention can be used in extremely cold environments (temperatures from -30°C to -40°C) as a solvent-free drag-reducing and wear-resistant coating for the inner wall of pipes.

Description

Technical Field

[0001] This invention relates to the field of coatings, specifically to a drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments and its preparation method. Background Technology

[0002] With increasing environmental protection efforts, the demand for natural gas is growing rapidly, leading to the commencement of numerous large-scale natural gas transmission projects in recent years. Applying drag-reducing coatings to the inner walls of long-distance transmission pipelines reduces energy consumption, saves energy, and reduces emissions, resulting in significant overall economic benefits. Furthermore, long-distance natural gas transmission pipelines are typically large-diameter steel pipes, incurring high construction and laying costs. In addition to economic benefits, drag-reducing coatings play a crucial role in preventing corrosion of the pipeline inner walls, improving wear resistance, and extending the pipeline's service life.

[0003] Currently, the main types of coatings used on the inner walls of natural gas pipelines are solvent-based and solvent-free. Solvent-based drag-reducing coatings have high VOC content, polluting the environment, and their overall performance is lower than that of solvent-free drag-reducing coatings. Furthermore, most current solvent-free drag-reducing coatings still have significant room for improvement in terms of surface resistance, wear resistance, and corrosion resistance.

[0004] Patent application CN202310106473.9 discloses an energy-saving, drag-reducing, wear-resistant, and corrosion-resistant solvent-free coating for the inner wall of natural gas pipelines, its preparation method, and its application. The energy-saving, drag-reducing, wear-resistant, and corrosion-resistant solvent-free coating for the inner wall of natural gas pipelines, by mass percentage, comprises: component A containing 25-35% epoxy resin, 20-25% fluorosilicone hybrid epoxy resin, 5-10% epoxy reactive diluent, 23-40% modified filler, 0.4-1% anti-settling agent, 0.3-0.5% leveling agent, and 0.3-0.6% defoamer; component B containing 100% aliphatic amine adduct. Although this coating has good wear and corrosion resistance, it cannot withstand extremely cold environments. It is prone to cracking and peeling at temperatures below -30℃, causing coating failure and rendering it unusable.

[0005] Patent CN201010541246.1 discloses a solvent-free coating for reducing drag and wear resistance in pipelines, its preparation method, and its application. The solvent-free coating comprises components A and B, with the following mass percentages: Component A: 30-40% epoxy resin, 5-10% toughening resin, 4-8% each of reactive diluent and zinc phosphate, 0.2-0.5% each of leveling agent and defoamer, 0.4-0.8% dispersant, 0.2-1.0% anti-settling thickener, 8-20% iron oxide red powder, and 5-15% each of aluminum tripolyphosphate and white ceramic magnetic powder; Component B: 5-20% modified amine and 2-10% modified polyamide; Components A and B are used in a mass ratio of 3-5:1. Although this coating exhibits good adhesion, flexibility, and resistance to salt spray and solvents, it cannot withstand extremely cold environments, and the solution cracks and peels off at temperatures below -30℃.

[0006] The above-mentioned existing coating technologies are all suitable for normal ambient temperatures (winter temperatures above -20℃), with an average temperature generally above 10℃. These coatings cannot withstand extremely cold environments for extended periods. If used in environments below -30℃ for a long time, the free volume of the three-dimensional cross-linked network of the epoxy coating on the inner wall of the pipe gradually decreases. The reduced intermolecular spacing decreases the chain segment mobility. Under these conditions, the long-term stress caused by the curvature of the inner wall will lead to stress concentration and breakage within the chain segments. This will result in leaks, cracks, and even peeling off the coating.

[0007] With the development of my country's oil and gas pipeline engineering, pipeline projects in extremely cold environments (temperatures between -30℃ and -40℃) have gradually been undertaken. Currently, solvent-free pipeline drag-reducing coatings are primarily suitable for temperate and subtropical environments, and are unsuitable for pipelines operating in extremely cold conditions. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments, its preparation method, and its application. This coating exhibits excellent flexibility in extremely cold environments (-40℃), allowing it to bend at a 2.5-degree angle without cracking; its adhesion can reach over 20 MPa; and it also possesses excellent freeze-thaw cycle resistance. This coating can operate long-term in extremely cold environments ranging from -30℃ to -40℃.

[0009] The objective of this invention can be achieved through the following technical solution: a drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments, comprising component A and component B, wherein the mass percentages of components A and B are as follows:

[0010] Component A:

[0011] Epoxy resin 15.0%–25.0%;

[0012] Modified resin 15.0–25.0%;

[0013] Reactive diluent 8.0–15.0%;

[0014] TDI adduct 0.5–2.0%;

[0015] Leveling agent 0.2-0.5%;

[0016] Defoamer 0.2-0.5%;

[0017] Dispersant 0.4-0.8%;

[0018] Bentonite 0.2–1.0%;

[0019] Zinc phosphate 5.0–15.0%;

[0020] Silicon carbide 3.0–15.0%;

[0021] Iron oxide red 5.0–10.0%;

[0022] Kaolin content: 5.0–10.0%;

[0023] 5.3%–15.2% silica powder;

[0024] Component B:

[0025] Modified amine 99.0%–99.8%;

[0026] Thixotropic synergist 0.2-1.0%.

[0027] Furthermore, the components A and B are used in combination at a mass ratio of A:B = 4.5 to 6:1.

[0028] Furthermore, the epoxy resin is an epoxy resin with an epoxy equivalent of 185-200, including at least one of E-51, CYD128, 828, or epoxy resins with a similar epoxy equivalent.

[0029] Furthermore, the modified resin is a polyurethane-modified epoxy resin, including CVC's polyurethane-modified epoxy resin HyPox UA11, etc. This resin, through grafting with an appropriate proportion of polyurethane soft segments, forms an interpenetrating polymer network structure by entanglement between the epoxy resin molecular chains and the polyurethane soft segments. This structure allows it to slip relative to the molecular chains when subjected to external forces, much like linear molecules. Therefore, disrupting the interpenetrating polymer network structure requires more energy, resulting in a good toughening effect.

[0030] The TDI adduct is a polyurethane curing agent containing NCO reactive groups, including L-75T from Hangzhou Baochen Chemical Co., Ltd. This invention uses the polyurethane curing agent in the resin component of the coating, allowing its NCO groups to undergo partial prepolymerization with the epoxy groups in the resin and the polyol in HyPox UA11, generating a three-dimensional network structure containing polyurethane-isocyanurate-epoxy groups. This structure increases free volume at low temperatures, relieving system stress and improving the mobility of molecular chain segments, thereby significantly improving fracture toughness at low temperatures.

[0031] Furthermore, the active diluent is one or two of the following: a multifunctional glycidyl ether resin, propylene oxide butyl ether, and ethylene glycol diglycidyl ether.

[0032] Furthermore, the leveling agent is an organosilicon-based BYK358N; the defoamer is an organosilicon-based BYK054 defoamer; the dispersant is BYK 163; and the bentonite-based thixotropic agent is Rockwood 1958.

[0033] Furthermore, the modified amine is an epoxy resin curing agent of phenolic modified amine;

[0034] The thixotropic synergist is BYK-R605, a liquid thixotropic enhancer for hydrophilic fumed silica. BYK-R605 is used in component B mainly to avoid its excessive viscosity in component A, which would make it difficult to apply. After components A and B are mixed, the active substances in BYK-R605 are distributed as fine crystals. Through the formation of hydrogen bonds and association with the coating, a stable pseudoplastic three-dimensional spatial structure can be quickly formed, resulting in excellent anti-sagging properties.

[0035] Furthermore, reaction-sintered silicon carbide of 800-1000 mesh is selected, which has high hardness and good wear resistance.

[0036] Spherical silica powder is selected because it is a high-strength, high-hardness, inert spherical particle with extremely low oil absorption, easy dispersion, and high wear resistance.

[0037] Adding silicon carbide, silicon micro powder, and kaolin to the formulation of this invention helps to improve the wear resistance and corrosion resistance of the coating.

[0038] This invention also provides a method for preparing a drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments, comprising the following steps:

[0039] Preparation of Component A: Mix epoxy resin, modified resin, and reactive diluent, and stir until homogeneous; add 50% TDI adduct while stirring continuously, and stir thoroughly for about 1 hour; add another 50% TDI adduct while stirring continuously, and stir thoroughly for about 1-2 hours to carry out prepolymerization reaction; add defoamer, leveling agent, and dispersant in sequence, and continue stirring and dispersing; add bentonite, increase the speed, and disperse at high speed; add zinc phosphate, silicon carbide, iron oxide red, kaolin, and silica powder in sequence while stirring at medium speed, increase the speed and continue stirring for 30 minutes; then grind to a fineness ≤45µm to obtain Component A.

[0040] Preparation of Component B: Modified fatty amine and thixotropic synergist were evenly dispersed to obtain Component B.

[0041] This invention also provides an application of a drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments. The coating is applied to oil or natural gas transmission pipelines in extremely cold environments as a drag-reducing and wear-resistant coating. Specifically, component A and component B are mixed evenly at a mass ratio of A:B = 4.5–6:1, and then coated onto the pipeline surface.

[0042] The pipeline can operate for extended periods in extremely cold environments ranging from -30°C to -40°C.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) Modified amine is used as curing agent, and polyurethane modified epoxy resin, epoxy resin, reactive diluent and TDI adduct are used as the main resin after prepolymerization reaction. Because the NCO group in TDI adduct can undergo partial prepolymerization reaction with the epoxy group in epoxy resin and the polyol in HyPox UA11 to generate a three-dimensional network structure containing polyurethane-isocyanurate-epoxy group. After the epoxy group in this structure undergoes ring-opening reaction with the active hydrogen of modified aliphatic amine, it is further crosslinked into a larger molecular weight and stronger network structure. This structure can further increase the free volume energy at low temperature to relieve system stress and improve the mobility of molecular chain segments, thereby significantly improving the fracture toughness at low temperature. Therefore, this coating has good flexibility, excellent adhesion, density and drag reduction and wear resistance under extremely cold temperature conditions;

[0045] (2) The product has good flexibility under extremely cold temperature conditions of -30℃ to -40℃. The dry film thickness of about 150 micrometers can pass the 3-degree bending test without cracking. The coating has excellent adhesion, and the adhesion can reach more than 20MPa in low temperature environment. The roughness Ra≤2μm (foreign products require Ra≤5μm) and wear resistance coefficient≥30 (foreign products require ≥23) make the coating have good drag reduction and wear resistance performance.

[0046] (3) Since the coating does not contain any volatile solvents, it can eliminate pinholes in the coating and improve its impermeability, abrasion resistance and corrosion resistance. Detailed Implementation

[0047] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0048] All raw materials used in this invention are commercially available products. For example, the raw materials selected in the following embodiments are as follows:

[0049] The epoxy resin used is Nan Ya 128 resin;

[0050] The modified resin used is CVC's HyPox UA10 resin.

[0051] The reactive diluent used is commercially available ethylene glycol diglycidyl ether;

[0052] The TDI adduct used is L-75T from Hangzhou Baochen Chemical Co., Ltd.

[0053] The leveling agent used is BYK-358N from BYK Corporation;

[0054] The defoamer used is BYK-054 from BYK Corporation;

[0055] The dispersant used is BYK163 from BYK Corporation;

[0056] The bentonite used was Rockwood's 1958.

[0057] Zinc phosphate is supplied by Shanghai Yipin Pigment Co., Ltd.

[0058] The silicon carbide used is a product of Shandong Yuzhi Huike New Materials.

[0059] The iron oxide red powder used is a product of Shanghai Yipin Pigment Co., Ltd.

[0060] The kaolin used is from Shanghai Yuanjiang Chemical Products.

[0061] The silicon micro powder is sourced from Shanghai Yuanjiang Chemical Co., Ltd.

[0062] The modified amine used was product D0965 from Shanghai Junjiang Technology.

[0063] The thixotropic synergist used is BYK-R605 from BYK Corporation.

[0064] Example 1

[0065] Component A:

[0066] Epoxy resin 15.0%;

[0067] Modified resin 25.0%;

[0068] Reactive diluent 12.0%;

[0069] TDI adduct 2.0%;

[0070] Leveling agent 0.5%;

[0071] Defoamer 0.2%;

[0072] Dispersant 0.8%;

[0073] Bentonite 1.0%;

[0074] Zinc phosphate 15.0%;

[0075] Silicon carbide 3.0%;

[0076] Iron oxide red powder 10.0%;

[0077] Kaolin 5.0%;

[0078] 10.5% silica powder;

[0079] Component B:

[0080] Modified amine 99.0%;

[0081] Thixotropic synergist 1.0%.

[0082] The coating is packaged in two components. During application, component A and component B are mixed at a weight ratio of 4.5:1.

[0083] (2) The preparation method of the drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments includes the preparation steps of component A and component B.

[0084] The preparation steps for component A are as follows:

[0085] Mix epoxy resin, modified resin, and reactive diluent until homogeneous. Add 50% TDI adduct while continuously stirring, and stir thoroughly for about 1 hour. Add another 50% TDI adduct while continuously stirring, and stir thoroughly at 600 rpm for about 1-2 hours to initiate a prepolymerization reaction. Add defoamer, leveling agent, and dispersant sequentially, and continue stirring at 600 rpm to disperse. Add bentonite, increase the stirring speed to 1000 rpm for high-speed dispersion. Add zinc phosphate, silicon carbide, iron oxide red, kaolin, and silica powder sequentially while stirring at a medium speed of 500 rpm. Increase the stirring speed to 800 rpm and continue stirring for 30 minutes. Finally, grind to a fineness ≤45µm to obtain component A.

[0086] The preparation steps for component B are as follows:

[0087] The modified fatty amine and thixotropic synergist were dispersed evenly to obtain component B.

[0088] Example 2

[0089] This embodiment provides a drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments. The coating comprises component A and component B. The raw materials and proportions (by weight percentage) of component A are shown below:

[0090] Component A:

[0091] Epoxy resin 25.0%;

[0092] Modified resin 15.0%;

[0093] 8.0% reactive diluent;

[0094] TDI adduct 0.5%;

[0095] Leveling agent 0.2%;

[0096] Defoamer 0.5%;

[0097] Dispersant 0.4%;

[0098] 0.2% bentonite;

[0099] Zinc phosphate 5.0%;

[0100] Silicon carbide 15.0%;

[0101] Iron oxide red powder 5.0%;

[0102] Kaolin 10.0%;

[0103] 15.2% silica powder;

[0104] Component B:

[0105] Modified amine 99.8%;

[0106] Thixotropic synergist 0.2%;

[0107] During the application of the coating, component A and component B in this embodiment are mixed at a weight ratio of 5:1.

[0108] (2) Specific preparation steps

[0109] (Same as Example 1).

[0110] Example 3

[0111] This embodiment provides a drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments. The coating comprises component A and component B. The raw materials and proportions (by weight percentage) of component A are shown below:

[0112] Component A:

[0113] Epoxy resin 20.0%;

[0114] Modified resin 22.0%;

[0115] Reactive diluent 15.0%;

[0116] TDI adduct 1.5%;

[0117] Leveling agent 0.4%;

[0118] Defoamer 0.4%;

[0119] Dispersant 0.6%;

[0120] Bentonite 0.8%;

[0121] Zinc phosphate 12.0%;

[0122] Silicon carbide 10.0%;

[0123] Iron oxide red powder 6.0%;

[0124] Kaolin 6.0%;

[0125] 5.3% silica powder;

[0126] Component B:

[0127] Modified amine 99.6%;

[0128] Thixotropic synergist 0.4%;

[0129] During the application of the coating, component A and component B in this embodiment are mixed at a weight ratio of 6:1.

[0130] (2) Specific preparation steps

[0131] (Same as Example 1).

[0132] This experiment will test the performance of the coatings in Examples 1 to 3 of the present invention, observe the coatings and record the test results as follows.

[0133] Experimental sample: Steel plate test strip with a coating thickness of approximately 150 micrometers;

[0134] Freeze-thaw cycle resistance test method: A steel plate test strip with a coating thickness of approximately 150 micrometers is placed in a -60℃ low-temperature chamber for 24 hours, then quickly removed and placed in a 10℃ constant-temperature chamber for 24 hours, which is recorded as one cycle; this is repeated for 45 cycles. After the test, observe whether the coating exhibits chalking, cracking, peeling / blistering, or other phenomena, and compare the color changes and gloss reduction with the retained test sample.

[0135] In Table 1, the adhesion, roughness Ra, and wear resistance coefficient are all test results of the steel plate test strips after the freeze-thaw cycle performance test.

[0136] The performance test results of the coatings in Examples 1-3 are shown in Table 1 below: Table 1:

[0137]

[0138] As can be seen from the table above, the coating of this invention exhibits excellent flexibility in extremely cold environments, capable of withstanding a 3-degree bend without cracking; its adhesion can reach over 20 MPa; and the coating also demonstrates excellent resistance to freeze-thaw cycles. This coating can operate long-term in extremely cold environments ranging from -30℃ to -40℃. The above description is merely a preferred embodiment of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the concept of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A drag reducing abrasion resistant solventless coating for pipelines in extremely cold environments, characterized in that, Comprise A component and B component, the mass percentage of A component and B component raw materials are respectively: A component: Epoxy resin 15.0~25.0%; Modified resin 15.0~25.0%; Active diluent 8.0~15.0%; TDI adduct 0.5~2.0%; Leveling agent 0.2~0.5%; Defoaming agent 0.2~0.5%; Dispersant 0.4~0.8%; Bentonite 0.2~1.0%; Zinc phosphate 5.0~15.0%; Silicon carbide 3.0~15.0%; Iron oxide red 5.0~10.0%; Kaolin 5.0~10.0%; Silica powder 5.3~15.2%; B component: Modified amine 99.0~99.8%; Thixotropy synergist 0.2~1.0%; The modified resin is polyurethane modified epoxy resin.

2. The anti-fouling, solvent-free, drag-reducing, wear-resistant coating for pipes in extremely cold environments according to claim 1, characterized in that, The A component and the B component are used in combination with the mass ratio A:B = 4.5~6:

1.

3. The anti-fouling, anti-wear, solvent-free coating for pipes in polar climate according to claim 1, characterized in that, The epoxy resin is an epoxy resin with an epoxy equivalent weight of 185-200.

4. The drag-reducing and wear-resistant solvent-free coating for pipelines in extremely cold environments according to claim 1, characterized in that, The TDI adduct is a polyurethane curing agent containing NCO reactive groups.

5. The anti-fouling, anti-wear, solvent-free coating for pipes in polar climate according to claim 1, characterized in that, The active diluent is one or two of multifunctional glycidyl ether resin, propylene oxide butyl ether, and ethylene glycol diglycidyl ether.

6. The anti-fouling, solvent free, drag reducing coating for pipes in extreme cold environments as claimed in claim 1, wherein The leveling agent is silicone-based BYK358N; the defoaming agent is silicone-based BYK054 defoaming agent; the dispersant is BYK 163; the bentonite is Rockwood 1958.

7. The anti-fouling, anti-wear, solvent-free, drag-reducing coating for pipes in extremely cold environments according to claim 1, characterized in that, The modified amine is a phenolic modified amine epoxy resin curing agent; The thixotropy synergist is a liquid thixotropy enhancer BYK-R605 for hydrophilic fumed silica.

8. A process for the preparation of a drag reducing abrasion resistant solventless coating for pipes in extremely cold environments as claimed in any one of claims 1 to 7, characterized in that, Comprise the following steps: Preparation of A component: mix epoxy resin, modified resin and active diluent, stir uniformly; under constant stirring, first add 50% of TDI adduct, stir thoroughly for 1 hour; under constant stirring, add another 50% of TDI adduct, stir thoroughly for 1-2 hours for prepolymerization; add defoaming agent, leveling agent, dispersant in sequence, continue to stir and disperse, add bentonite, increase the speed, disperse at high speed, add zinc phosphate, silicon carbide, iron oxide red, kaolin, silica powder in sequence under moderate stirring, increase the speed and continue to stir for 30 min, then grind to a fineness of ≤45 µm, to obtain A component; Preparation of B component: disperse modified fatty amine and thixotropy synergist uniformly to obtain B component.

9. Use of a drag reducing abrasion resistant solventless coating for pipes in extremely cold environments according to any one of claims 1-7, characterized in that, The coating is applied to petroleum or natural gas pipelines in extremely cold environments as a drag-reducing and wear-resistant coating.

10. Use of the drag reducing abrasion resistant solventless coating for pipes in polar environments according to claim 9, characterized in that, The pipeline can serve in extremely cold environments of -30℃~-40℃ for a long time.

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