Single-component high-wear-resistance anticorrosive paint, preparation method and application

Abstract

The invention belongs to the technical field of corrosion-resistant and wear-resistant materials for oil well sleeves, and relates to a single-component high-wear-resistant corrosion-resistant coating, a preparation method and application, the coating comprises the following components by mass: 23-31 parts of aromatic isocyanate, 20-24 parts of polycarbonate polyol, 31-38 parts of a closed ammonia chain extender, 14-20 parts of a pigment, 1-3 parts of fumed silica, 30-40 parts of a diluent, and 1-2 parts of an auxiliary agent; the auxiliaries comprise a dispersing agent, a defoaming agent, a wetting agent and a catalyst; the molecular weight of the polycarbonate polyol is 1000 to 2000; by controlling the content of the hard segment and the content of the soft segment, the balance of high wear resistance and high impact toughness is realized, and meanwhile, good binding force between the coating and a metal substrate is ensured. Therefore, the single-component high-wear-resistance anticorrosive paint has wide application prospects and remarkable economic benefits in the field of spraying of oil field and oil well equipment.

Description

Technical Field

[0001] This invention belongs to the technical field of anti-corrosion and wear-resistant materials for oil well casings, specifically relating to a single-component high wear-resistant and anti-corrosion coating, its preparation method, and its application. Background Technology

[0002] Oil wells can reach depths of several kilometers, and the internal conditions are complex, containing oil, water, and sediment. This places high demands on well casings, requiring them to offer excellent corrosion resistance, as well as high wear resistance, heat resistance, solvent resistance, and impact resistance. Especially when lowering equipment into the casing, the multi-section, non-vertical nature of the casing means that the heavy equipment frequently rubs against and collides with it, causing damage. The inner wall of well casings is typically coated with an anti-corrosion layer. Existing anti-corrosion coatings for oilfield casings are diverse, but most are epoxy-based, including powder epoxy coatings and solvent-based epoxy coatings, often employing phenolic epoxy systems for better heat and solvent resistance.

[0003] However, while existing anti-corrosion coatings for oilfield sleeves meet the requirements for solvent and heat resistance, their impact resistance and wear resistance fall far short of the requirements in long-term practical applications. After repeated large impacts and friction, the existing anti-corrosion coatings on oilfield sleeves frequently break down, unable to withstand such violent impacts, ultimately leading to sleeve corrosion and eventual scrapping, causing significant economic losses. Although there are related solutions using alloy steel oilfield sleeves to address this problem, alloy steel is expensive and economically unfeasible, making large-scale application difficult.

[0004] Therefore, a new type of oilfield sleeve corrosion protection material with better wear resistance and impact resistance is needed to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides the following technical solution: a single-component high wear-resistant and anti-corrosion coating, comprising the following components in parts by weight: 23-31 parts of aromatic isocyanate, 20-24 parts of polycarbonate polyol, 31-38 parts of blocked ammonia chain extender, 14-20 parts of pigment, 1-3 parts of fumed silica, 30-40 parts of diluent, and 1-2 parts of additives; the additives include: dispersant, defoamer, wetting agent, and catalyst; the molecular weight of the polycarbonate polyol is 1000-2000.

[0006] Preferably, the aromatic isocyanate includes: polymethylene polyphenyl polyisocyanate and / or 4,4'-diphenylmethane diisocyanate.

[0007] Preferably, the blocked ammonia chain extender is a dispersion of an aromatic diamine containing a benzene ring and sodium chloride.

[0008] Preferably, the pigment comprises one or more of basalt flakes, zinc strontium phosphate, and zinc aluminum polyphosphomolybdate; the diluent comprises one or more of divalent esters, ethylene glycol diacetate, and propylene glycol methyl ether acetate; the catalyst comprises glycerol; the wetting agent is Tego WET KL245; the defoamer is Tego Airex940; the dispersant is BYK110; the fumed silica is A380; and the additives comprise the following components in parts by weight: 0.4–1.1 parts dispersant, 0.2–0.3 parts defoamer, 0.3–0.4 parts wetting agent, and 0.2–0.3 parts catalyst.

[0009] The mass fractions of each component in the pigment are: 8-12 parts basalt flakes, 1.5-2.5 parts zinc strontium phosphate, and 0-8 parts aluminum zinc polyphosphomolybdate.

[0010] This invention also discloses a method for preparing a single-component high-wear-resistant and anti-corrosion coating. This method, used to prepare the aforementioned single-component high-wear-resistant and anti-corrosion coating, includes the following steps: Synthesis of semi-prepolymer: Weigh polycarbonate polyol and put it into a reaction vessel. After dehydration under reduced pressure at 100-120℃ for 0.5-1.5 hours, cool down to 55-65℃, slowly add aromatic isocyanate and react for 20-40 minutes. Then slowly heat up to 65-75℃ and keep warm for 1.5-2.5 hours. Take a sample and test the free NCO content. It is 12%-15%, and the semi-prepolymer is obtained.

[0011] Grinding and mixing: The synthesized semi-prepolymer is put into a sand mill for grinding, and dried and dehydrated pigments, additives, fumed silica, diluents, and blocked ammonia chain extenders are added. Circulating cooling water is used to cool the material so that the temperature inside the sand mill does not exceed 70°C. After the fineness reaches 80μm, the material is filtered and discharged.

[0012] Preferably, in the step of synthesizing the semi-prepolymer, the free NCO content is sampled and tested to be 12% to 15% to obtain the semi-prepolymer.

[0013] This application also discloses an application of a single-component high wear-resistant and corrosion-resistant coating, wherein the application uses the above-mentioned single-component high wear-resistant and corrosion-resistant coating for spraying on oilfield well equipment.

[0014] Preferably, the implementation steps for spraying the oilfield well equipment include: Step 1, Substrate treatment: The metal substrate is shot blasted to remove rust and oil, achieving Sa2.5 grade and a roughness Ra range of 60-100μm.

[0015] Step 2: Apply the single-component high wear-resistant and anti-corrosion coating using a high-pressure airless sprayer with a spraying pressure of 15-20 MPa and a spray gun nozzle diameter of 0.3-0.5 μm; or apply the single-component high wear-resistant and anti-corrosion coating using an air sprayer with a spraying pressure of 0.3-0.5 MPa.

[0016] Step 3: After spraying, heat the sprayed parts to 80-85℃ and keep them warm for 2-3 hours, then raise the temperature to 100-105℃ and keep them warm for another 8-10 hours.

[0017] The beneficial effects of this invention are: 1. This invention, through a unique polyurethane system design, significantly improves the wear resistance and impact resistance of the coating. Compared to traditional wear-resistant epoxy coatings, the coating of this invention performs excellently in the Taber abrasion test, with a significantly reduced abrasion loss and greatly improved wear resistance. Simultaneously, the impact toughness of the polyurethane is also significantly enhanced, enabling the coating to better protect the substrate when facing external impacts.

[0018] 2. This invention uses a blocked ammonia chain extender, which effectively solves the problem of excessively fast reaction between aromatic ammonia chain extenders and aromatic isocyanates, allowing the coating to be made into a single component, greatly improving the convenience of spray application. Detailed Implementation

[0020] This embodiment uses a polyurethane system as the protective layer of the sleeve. Polyurethane has higher wear resistance and impact resistance than epoxy materials. The Taber wear of commonly used wear-resistant epoxy coatings is 30-60mg (CS-17 wheel, 1kg, 1000r), while the wear of the polyurethane system in this embodiment is only 2mg under the same conditions, which greatly improves the wear resistance. At the same time, the impact toughness of polyurethane is also greatly improved.

[0021] The single-component high abrasion-resistant and anti-corrosion coating of this embodiment comprises aromatic isocyanates (MDI and PAPI, i.e., 4,4'-diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate), polycarbonate polyol, blocked ammonia chain extender, pigment, fumed silica (i.e., fumed silica), diluent, and additives (dispersant, wetting agent, defoamer, catalyst). Aromatic isocyanates contain benzene rings, providing abrasion resistance, heat resistance, and strength. Through polymerization modification with polycarbonate polyol, abrasion resistance and impact toughness can be improved. Blocked ammonia chain extenders provide abrasion resistance, heat resistance, and solvent resistance. The presence of a large number of benzene rings in the system provides a sufficiently high hard segment content. Simultaneously, due to the functionality of PAPI (2.7), moderate crosslinking is provided, offering better heat resistance, corrosion resistance, and solvent resistance. The high hardness content gives the coating both high hardness and satisfactory impact toughness, and its overall performance completely surpasses that of phenolic epoxy systems.

[0022] Because the reaction rate between aromatic amine chain extenders and aromatic isocyanates is very fast, usually only a few seconds, it is difficult to apply coatings with a thickness of only 300 micrometers or less. This invention uses a blocked amine chain extender to block the amino group. When heated, the amino group is released and can quickly participate in the reaction. When not heated, the blocked amine chain extender and aromatic isocyanate do not react. Therefore, it can be made into a single-component anti-corrosion coating, which greatly improves the convenience of spray application.

[0023] Referring to the industry standard of China National Petroleum Corporation, SY / T 6717-2016 Technical Conditions for Inner Coating of Tubing and Casing, and in conjunction with the standard of a certain oilfield enterprise, the material of this invention needs to meet the following performance requirements. The basic performance requirements of the material are shown in Table 1 below: The MDI used in this invention is 4,4'-diphenylmethane diisocyanate, the PAPI is polymethylene polyphenyl polyisocyanate, the polycarbonate polyol is a difunctional polyol with a molecular weight of 1000-2000, and the blocked ammonia chain extender is a dispersion of a benzene-ring-containing aromatic diamine and sodium chloride with an ammonia equivalent of 150-300 g / mol. The rust-preventive pigment is a mixture of basalt flakes, zinc strontium phosphate, and zinc aluminum polyphosphomolybdate. The diluent is one or more of the following environmentally friendly divalent esters: ethylene glycol diacetate (EGDA) and propylene glycol methyl ether acetate (PMA). The catalyst is glycerol.

[0024] The present invention provides a single-component high wear-resistant and anti-corrosion coating comprising the following components in parts by weight: 23-31 parts aromatic isocyanate, 20-24 parts polycarbonate polyol, 31-38 parts blocked ammonia chain extender, 14-20 parts pigment, 1-3 parts fumed silica, 30-40 parts diluent, and 1-2 parts additives.

[0025] The pigment comprises the following components in parts by weight: 8-12 parts basalt flakes, 1.5-2.5 parts zinc strontium phosphate, and 0-8 parts zinc aluminum polyphosphomolybdate.

[0026] The additives comprise the following components in parts by weight: 0.4 to 1.1 parts dispersant, 0.2 to 0.3 parts defoamer, 0.3 to 0.4 parts wetting agent, and 0.2 to 0.3 parts catalyst.

[0027] The coating preparation process of this invention: 1. Synthetic semi-prepolymer: By weight, it comprises 23-31 parts aromatic isocyanate and 20-24 parts polycarbonate polyol. The aromatic isocyanate includes one or a mixture of two of polymethylene polyphenyl polyisocyanate and / or 4,4'-diphenylmethane diisocyanate. The polycarbonate polyol has a molecular weight of 1000-2000 and a functionality of 2. The NCO content of the semi-prepolymer must be controlled at 12%-15%. Excessive NCO content results in a brittle material with poor impact resistance, while insufficient NCO content reduces the material's heat resistance, chemical resistance, and adhesion, failing to meet standards.

[0028] Weigh a certain amount of polycarbonate polyol by weight and put it into a reaction vessel. Dehydrate it under reduced pressure at 100-120℃ for 1 hour, then cool it down to 60℃, and slowly add aromatic isocyanate. After reacting for half an hour, slowly raise the temperature to 70℃ and keep it at that temperature for 2 hours. Take a sample to test the free NCO content.

[0029] 2. Grinding and mixing The synthesized semi-prepolymer is fed into a sand mill, and dried and dehydrated anti-rust pigments, diluents, dispersants, wetting agents, defoamers, catalysts, glycerol, gaseous silicon, blocked ammonia chain extenders are added in proportion. Circulating cooling water is used to cool the material so that the temperature inside the sand mill does not exceed 70℃. After the fineness reaches 80μm, the material is filtered and discharged.

[0030] Blocked ammonia chain extenders are beneficial for construction and can be made into single-component materials.

[0031] Zinc strontium phosphate rust-inhibiting pigments offer excellent corrosion resistance and anti-foaming effects. Basalt flakes are superior barrier-type flake rust-inhibiting pigments, using 400-800 mesh basalt flakes. The polyphosphate groups in polyphosphoric aluminum molybdate rust-inhibiting pigments have strong metal chelating properties, while aluminum molybdate has strong metal oxidizing capabilities; these multiple effects contribute to the excellent rust-preventing effect of this type of rust-inhibiting pigment. Gas silica has anti-precipitation and anti-sagging properties; Evonik Degussa's gas silica A380 is selected, resulting in low dust dispersion during production. The substrate wetting agent used is Tego WET KL245. The defoamer used is Tego 940 high-efficiency defoamer. The dispersant used is BYK110 from BYK Chemicals. The blocked ammonia chain extender used is XYlink 311 from Suzhou Xiangyuan New Materials Co., Ltd.

[0032] Construction process of the present invention: 1. Substrate treatment: First, the metal substrate is shot blasted to remove rust and oil, reaching Sa2.5 grade, with a roughness Ra range of 60-100μm. Low roughness will affect the bonding strength.

[0033] 2. Use a high-pressure airless sprayer with a spraying pressure of 15-20 MPa and a spray gun nozzle diameter of 0.3-0.5 μm; an air sprayer can also be used with a spraying pressure of 0.3-0.5 MPa.

[0034] 3. After the spraying is completed, the pipe is placed in the heating furnace for heating. The closed ammonia chain extender in the system of this invention begins to open and release ammonia at 80°C, and then reacts rapidly with aromatic isocyanate. Therefore, the heating temperature is first 80°C for two hours, and then the temperature is raised to 100°C and heated for another 8 hours before it can be taken out of the furnace.

[0035] Example 1: Preparation scheme 1 for a single-component high wear-resistant and anti-corrosion coating: (1) Synthesis of semi-prepolymer The polycarbonate polyol used is Asahi Kasei's highly chemical-resistant bio-based PCD, model BP002, with a molecular weight of 2000 and a hydroxyl equivalent of 1000. 23.5 parts of polycarbonate polyol were weighed and added to the reactor. The mixture was dehydrated under reduced pressure at 100-120°C for 1 hour, then cooled to 60°C. 23.5 parts of aromatic isocyanate PAPI (PM200 from Yantai Wanhua) were then slowly added. After reacting for half an hour, the temperature was slowly raised to 70°C and held for 2 hours. When the free NCO mass percentage reached 13.45%, the next step was carried out.

[0036] (2) Grinding and mixing The synthesized semi-prepolymer is fed into a sand mill, and dried and dehydrated anti-rust pigment, closed ammonia chain extender, diluent, dispersant, defoamer, catalyst silicone oil, gaseous silicon, and circulating cooling water are added in proportion to cool the material so that the temperature inside the sand mill does not exceed 70℃. After the fineness reaches 80μm, the material is filtered and discharged.

[0037] The specific proportions are shown in Table 2 below: The performance test results are shown in Table 3 below: Example 2, Preparation scheme 2 for single-component high wear-resistant and anti-corrosion coating: (1) Synthesis of semi-prepolymer The polycarbonate polyol used is Asahi Kasei's highly chemical-resistant bio-based PCD, model PCDX259, with a molecular weight of 1000 and a hydroxyl equivalent of 510. 20.086 parts of polycarbonate polyol were weighed and added to the reactor. The mixture was dehydrated under reduced pressure at 100-120°C for 1 hour, and then cooled to 60°C. 13.695 parts of aromatic isocyanate PAPI (PM200 from Yantai Wanhua) and 11.869 parts of 4,4'-diphenylmethane diisocyanate, referred to as MDI, were then added. MDI used was MDI100 from Yantai Wanhua. After reacting for half an hour, the temperature was slowly raised to 70°C and held for 2 hours. When the free NCO content reached 14.4%, the next step was carried out.

[0038] (2) Grinding and mixing The synthesized semi-prepolymer was fed into a sand mill, along with dried and dehydrated rust-preventive pigments, diluents, wetting agents, dispersants, defoamers, catalyst glycerol, fumed silica, and blocked ammonia chain extenders, all added in the specified proportions. Circulating cooling water was used to cool the material, ensuring the temperature inside the sand mill did not exceed 70℃. After the particle size reached 80μm, the material was filtered and discharged. Specific proportions are shown in Table 4 below. The performance test results are shown in Table 5 below: Example 3, Preparation scheme 3 for single-component high wear-resistant and anti-corrosion coating: (1) Synthesis of semi-prepolymer The polycarbonate polyol used is Asahi Kasei's highly chemical-resistant bio-based PCD, model PCDX259, with a molecular weight of 1000 and a hydroxyl equivalent of 510. 21.6 parts of polycarbonate polyol were weighed and added to the reactor. The mixture was dehydrated under reduced pressure at 100-120°C for 1 hour, then cooled to 60°C. 23.4 parts of aromatic isocyanate PAPI (PM200 from Yantai Wanhua) were then slowly added. After reacting for half an hour, the temperature was slowly raised to 70°C and held for 2 hours. When the free NCO content reached 12.2%, the next step was carried out.

[0039] (2) Grinding and mixing The synthesized semi-prepolymer was fed into a sand mill, along with dried and dehydrated rust-preventive pigments, diluents, dispersants, wetting agents, defoamers, catalyst glycerol, fumed silica, blocked ammonia chain extenders, and circulating cooling water to cool the material, ensuring the temperature inside the sand mill did not exceed 70℃. After the particle size reached 80μm, the material was filtered out. Specific proportions are shown in Table 6 below. The performance test results are shown in Table 7: The material properties of this invention are compared with those of a certain listed group's special oilfield sleeve epoxy phenolic powder anti-corrosion coating, and with those of a well-known foreign company's high corrosion-resistant and wear-resistant epoxy glass flake coating, as shown in Table 8 below: This invention relates to a polyurethane high-wear-resistant material. By controlling the content of hard segments and soft segments, high wear resistance and high impact toughness can be achieved. The bonding strength between polyurethane and metal is generally weaker than that of epoxy materials. This invention requires a sufficiently high shot-blasting roughness of the substrate (above 60 μm) and high material hardness, which, according to testing, meets these requirements.

[0040] In summary, this invention achieves a balance between high wear resistance and high impact toughness by controlling the content of hard and soft segments, while ensuring good adhesion between the coating and the metal substrate. Therefore, the single-component high wear-resistant anti-corrosion coating of this invention has broad application prospects and significant economic benefits in the field of oilfield well equipment spraying.

[0041] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A single component high abrasion resistant anticorrosive coating characterized in that, The components include the following mass fractions: aromatic isocyanate 23-31 parts, polycarbonate polyol 20-24 parts, blocked ammonia chain extender 31-38 parts, pigment 14-20 parts, fumed silica 1-3 parts, diluent 30-40 parts, auxiliary 1-2 parts; the auxiliary includes dispersant, defoamer, wetting agent, catalyst; The molecular weight of the polycarbonate polyol is 1000-2000.

2. The one-component high wear resistant anticorrosive paint according to claim 1, characterized in that, The aromatic isocyanate includes polymethylene polyphenyl polyisocyanate and / or 4,4'-diphenyl methane diisocyanate.

3. The one-component high wear resistant anticorrosive paint according to claim 1, characterized in that, The blocked ammonia chain extender is an aromatic diamine containing a benzene ring and a sodium chloride dispersion.

4. The one-component high wear resistant anticorrosive paint according to claim 1, characterized in that, The pigment includes one or more of basalt flakes, zinc strontium phosphate, and polyaluminum zinc molybdate; the diluent includes one or more of divalent acid ester, ethylene glycol diacetate, and propylene glycol methyl ether acetate; the catalyst includes glycerol; the wetting agent is Tego WETKL245, the defoamer is Tego Airex940, the dispersant is BYK110; and the fumed silica is A380. The auxiliary includes the following mass fractions of components: dispersant 0.4-1.1 parts, defoamer 0.2-0.3 parts, wetting agent 0.3-0.4 parts, catalyst 0.2-0.3 parts. The mass fractions of each component in the pigment are: basalt flakes 8-12 parts, zinc strontium phosphate 1.5-2.5 parts, and polyaluminum zinc molybdate 0-8 parts.

5. A process for the preparation of a single component high abrasion resistant anticorrosive coating characterized in that, The preparation method is used to prepare the single-component high-wear-resistant anticorrosive coating of any one of claims 1-4, and the preparation method comprises the following steps: Synthesizing a semi-prepolymer: polycarbonate polyol is weighed and placed in a reaction kettle, dehydrated at 100-120°C under reduced pressure for 0.5-1.5 hours, then cooled to 55-65°C, slowly added with aromatic isocyanate and reacted for 20-40 minutes, then slowly heated to 65-75°C and kept for 1.5-2.5 hours, sampled and tested for free NCO content of 12%-15%, and a semi-prepolymer is obtained; Grinding and mixing: the synthesized semi-prepolymer is placed in a sand mill for grinding, and the pigment, auxiliary, fumed silica, diluent, and blocked ammonia chain extender after drying and dehydration are also placed in the sand mill, and the circulating cooling water is used to cool the materials so that the temperature in the sand mill does not exceed 70°C, and the material is filtered out after the fineness reaches 80μm.

6. The method of claim 5, wherein the one-component high wear-resistant anticorrosive coating is prepared by adding 0.1 to 1.0 parts by weight of the compound of formula (I) to 100 parts by weight of the base paint. In the step of synthesizing a semi-prepolymer, the free NCO content is sampled and tested to be 12%-15%, and a semi-prepolymer is obtained.

7. Use of a single-component, high-wear-resistant anticorrosive coating, characterized in that The single-component high-wear-resistant anticorrosive coating of any one of claims 1-4 is used for oilfield well equipment spraying.

8. Use of a one-component high abrasion resistant anticorrosive coating according to claim 7, characterized in that, The implementation steps of the oilfield well equipment spraying include: Step 1: substrate treatment: the metal substrate is treated by shot blasting, rust and oil removal, and reaches Sa2.5 level and roughness Ra range of 60-100μm; Step 2: the single-component high-wear-resistant anticorrosive coating is sprayed by using a high-pressure airless sprayer, and the spraying pressure is 15-20MPa and the spraying gun caliber is 0.3-0.5μm; Alternatively, the single-component high-wear-resistant anticorrosive coating is sprayed by using an air sprayer, and the spraying pressure is 0.3-0.5MPa. Step 3, after the spraying is finished, the sprayed part is heated to 80-85℃ for 2-3 hours, and then heated to 100-105℃ for 8-10 hours.

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