Epoxy composition for a coating to which markings can be applied, metallic substrate coated with epoxy composition, epoxy composition-based coating with marking applied thereto

Abstract

The invention relates to the field of oil and gas production, and more particularly discloses the production of an epoxy composition for manufacture of a coating to which markings can be applied, which is adapted for use in aggressive conditions in oilfield tubulars and in pipelines for transporting oil and petroleum products. Proposed is an epoxy composition for a coating to which markings can be applied, said composition containing an epoxy base and a curing system. The epoxy base comprises, in the following proportions: 8-40 wt% bisphenol A-based and bisphenol F-based epoxy resins; 12-15 wt% titanium dioxide; 12-15 wt% micronized mica; 20-35 wt% silicon dioxide; 1-3 wt% ethylbenzene; 10-13 wt% xylene; 1.5-5 wt% 2-methylpropan-1-ol; 0.1-2 wt% rheological additive; 0.5-2 wt% dispersant; 0.1-2 wt% deaerator, wherein the ratio of bisphenol A-based epoxy resin to bisphenol F-based epoxy resin is from 1:3 to 3:1. The curing system comprises, in the following proportions: 22-50 wt% N-1,1-diethyl-1,3-diaminopropane; 10-26 wt% benzyl alcohol; 3-10 wt% ethylbenzene; 6-10 wt% bisaminomethylbenzene; 5-10 wt% 3-(2-aminoethylamino)propyltrimethoxysilane; 1-5 wt% 2-hydroxybenzoic acid; 12-15 wt% xylene; 5-10 wt% 2-methylpropan-1-ol. The ratio of the epoxy base to the curing system is from 2:1 to 12:1. The technical result is that of enhancing the wear-resistance of markings applied to the claimed epoxy coating on a metallic substrate and exposed to aggressive media such as oil, acids and alkalis at elevated pressures and temperatures, and also maintaining the adhesive properties of the coating.

Description

[0001] Epoxy coating composition for marking, metal substrate with an epoxy composition applied to it, coating with marking based on an epoxy composition

[0002] The invention relates to the field of oil and gas production, in particular the invention discloses the production of an epoxy composition for the manufacture of a coating with subsequent application of markings thereon, suitable for use in aggressive well conditions of oil and gas production for oil-grade pipes and linear pipeline pipes for the transportation of oil and petroleum products.

[0003] The problem of identifying and tracking tubing throughout all stages of its lifecycle has long been a persistent one. The lifecycle of tubing, which begins at the manufacturing plant and ends with its disposal, can also include repeated trips into the well and repairs after the pipe has been in service. Traditional methods of identifying tubular goods, such as applying markings to the pipe surface using paint, laser, or peen, are unsuitable for the operating conditions of oil production pipes. Finding and recognizing traditional pipe markings can be difficult or even impossible due to their poor resistance to operating conditions.

[0004] Radio-frequency identification (RFID) technology, which involves placing an RFID tag on the pipe, is often used to address this issue. However, this is an expensive and not always feasible method. This method has poor performance in the presence of radio-opaque and radio-absorbing objects. Current RFID technology performs poorly with such materials, and in some cases, fails completely. Furthermore, environmental conditions can negatively impact RFID solutions.

[0005] Therefore, one of the challenges in the oil and gas industry is providing oil country tubular goods with protective coatings that not only offer corrosion resistance in aggressive corrosive environments but also enable the application of environment-resistant markings, enabling the entire lifecycle of the pipes to be tracked from production to disposal. An anti-corrosion coating for protecting the inner surface of pipes, a composition for producing it, and a method for producing it are known in the prior art (see RU 2805934, published October 24, 2023). A base for a two-component mixture for producing an anti-corrosion coating is known, comprising components in the following ratio:parts: bisphenol A / P-(epichlorohydrin) epoxy resin 5-25; xylene 10-13; isobutanol 1-5; ethylbenzene 1-3; a filler selected from the group consisting of titanium dioxide, calcined kaolin, inert quartz filler and mixtures thereof 35-70; rheological additive 0.1-1.0; dispersant 0.1-1.5; deaerator 0.1-2.0. In this case, the filler is a mixture of titanium dioxide, calcined kaolin and finely dispersed quartz in a weight ratio of titanium dioxide: calcined kaolin: finely dispersed quartz = 10-15: 10-25: 15-30. The rheological additive is a solution of polyamide modified with urea. The dispersant is a polyolefin. The deaerator is a polyacrylate-based additive.

[0006] A hardener for a two-component mixture for obtaining an anti-corrosion coating, including components in the following ratio, in parts by weight: xylene 20-25; 1-1,1-diethyl-1,3-diaminopropane 10-20; benzyl alcohol 7-25; isobutanol 5-10; ethylbenzene 3-7; bis(aminomethyl)benzene 3-5; 3-(2-aminoethylamino)propyltrimethoxysilane 2-5; 2-hydroxybenzoic acid 1-3.

[0007] The known coating is applied to the inner surface of pipes and maintains its adhesive properties in aggressive environments at elevated temperatures. However, the known document contains no information that this coating will retain its properties when applied to the outer surface of pipes. Furthermore, the known patent does not disclose the possibility of applying markings to the surface of a pipe coated with an anti-corrosion coating or ensuring that the engraving / marking remains stable in aggressive environments.

[0008] A prior art method for applying laser markings to pipes in the oil industry is known (see the article "MARKING DRILL PIPES WITH SIC MARKING EQUIPMENT," published April 18, 2016). The article discusses the advantages of applying a Unique Product Identifier (UPI) to pipes used in the oil industry.

[0009] However, markings applied to metal pipes quickly deteriorate when exposed to aggressive environments, making it impossible to identify the pipes after several operating cycles. The technical problem addressed by this invention is the insufficient durability of markings on oilfield pipes operating in aggressive environments.

[0010] The technical result achieved by using the claimed invention consists in increasing the abrasion resistance of markings applied to an epoxy coating, which is applied to a metal substrate, in aggressive environments such as oil, acids, alkalis at elevated pressure and temperature, while simultaneously maintaining adhesive properties.

[0011] The technical problem is solved and the technical result is achieved due to an epoxy coating composition for applying markings, containing an epoxy base and a curing system, wherein the epoxy base includes components in the following ratio, wt.%: a mixture of epoxy resins based on bisphenol A and bisphenol F - 8-40, titanium dioxide 12-15, micronized mica 12-15, silicon dioxide 20-35, ethylbenzene 1-3, xylene 10-13, 2-methylpropan-1-ol 1.5-5, rheological additive 0.1-2, dispersant 0.5-2, deaerator 0.1-2, wherein the ratio of epoxy resins based on bisphenol A and bisphenol F is from 1:3 to 3:1; and, the curing system includes components in the following ratio, wt.%: 1-1,1-diethyl-1,3-diaminopropane 22-50, benzyl alcohol 10-26, ethylbenzene 3-10, bisaminomethylbenzene 6-10, 3-(2-minoethylamino)propyltrimethoxysilane 5-10, 2-hydroxybenzoic acid 1-5, xylene 12-15, 2-methylpropan-1-ol 5-10, while the ratio of epoxy base to curing system is: from 2: 1 to 12: 1.

[0012] It is preferred that the ratio of epoxy base to curing system is 5:1.

[0013] The proposed epoxy coating composition for marking is characterized by an optimally balanced ratio of its components, providing improved technological properties of the epoxy composition. This, in turn, facilitates the formation of a coating on a metal substrate based on the proposed composition with increased abrasion resistance, including the marking applied to this coating, even when the coatings with applied markings are used in aggressive environments such as oil, acids, and alkalis at elevated pressures and temperatures. Even small changes in the chemical structure of the source material molecules lead to significant differences in the properties of the resulting resins.Thus, the presence of a more flexible methylene bridge (-CH2-) in the bisphenol F structure compared to the structural fragment in diphenylolpropane (a bisphenol A-based resin) results in the formation of more elastic materials compared to epoxy diane resins. The increased resistance of materials based on bisphenol F glycidyl ethers to a wider range of chemically aggressive substances is explained by the fact that these systems, having higher functionality than bisphenol A-based resins, promote the formation of a more rigid three-dimensional crosslink with increased density during the formation of the cured material. Combining these resins in the proposed ratio allows for the production of epoxy composites with enhanced technological characteristics. Thus, when mixed, optimal viscosity is achieved for coating production and the absence of crystallization at low temperatures.

[0014] This ratio of bisphenol A and bisphenol F-based epoxy resins in the mixture allows for the production of coatings with good adhesion to metals, elasticity, and strength, which in turn prevents the coating with applied markings from peeling off the surface of the metal substrate, particularly oilfield pipes and pipelines. Thus, mixtures of bisphenol A and F-based resins combine the advantages of both components (medium viscosity, high cross-linking density, etc.), are highly processable, and allow for the production of various epoxy compositions, including those with high levels of dispersed fillers.

[0015] The use of dispersed fillers such as titanium dioxide, micronized mica, and silicon dioxide in the proposed ratios allows for the production of coatings with good adhesion to metal and increased resistance to aggressive environments. These coatings are easy to mark and retain markings for a long time, even in aggressive environments. Laser marking is preferred. These ratios of epoxy composition components enhance the properties of laser marking and also allow for high-contrast engraving / marking.

[0016] The technical problem is solved, and the technical result is also achieved, in the following specific embodiments. Epoxy resins based on bisphenol A and bisphenol F have a molecular weight greater than 700. The technical problem is also solved, and the technical result is achieved, by using a metal substrate coated with an epoxy coating composition for marking.

[0017] The technical problem is also solved, and the technical result is achieved, by using an epoxy-based coating with markings. It is preferable for the markings to be laser-applied to the epoxy coating to a depth of 40-60% of the average coating thickness. This coating ensures excellent adhesion to the metal substrate, and the markings applied to it remain intact for a long time, allowing for recognition even in aggressive environments at elevated temperatures and pressures.

[0018] Thanks to the use of an epoxy-based coating, the markings / engravings applied to it are not damaged during environmental testing simulating the operation of oil well tubing. These extremely harsh conditions cause the vast majority of coatings to lose their anti-corrosion properties within a short period of time, and markings on metal simply corrode within two to three months after application (the serial number of the pipe from the pipe factory). Furthermore, laser markings / engravings on the surface of the epoxy coating are produced in high resolution, are executed quickly, and are durable even in aggressive, corrosive environments.

[0019] Marking that is resistant to aggressive, corrosive environments allows for tracking the entire life cycle of a pipe, from production to disposal (inventory management, cost reduction).

[0020] A cloud-based pipe history database, accessible by the company's clients when using pipes with marked pipes, will allow them to understand the specific operating history based on the pipe's parameters, effectively build a pool of warehouse stock at pipe yards, and accurately identify defective pipes and / or pipes subjected to non-standard storage, operation, and repair procedures.

[0021] The following components are preferably used in the claimed epoxy coating composition for marking:

[0022] - epoxy resins such as YD-128 (manufacturer KUKDO Chemical Co., Ltd), ED-20 (GOST 10587-84), KER 828 (manufacturer KUMHO Chemicals), DER-331 (manufacturer Olin Epoxy (DOW)) and others can be used as epoxy resin based on bisphenol A (4,4'-dihydroxy-2,2-diphenylpropane) with a molecular weight of over 700;

[0023] - epoxy resins such as DER-3531, DEN 426, DER-352 (manufacturer Olin Epoxy (DOW)), Cetepox 200 R (manufacturer Aditya Birla Group), etc. can be used as epoxy resins based on bisphenol F with a molecular weight of over 700;

[0024] - the following can be used as fillers: titanium dioxide, for example, grades R-706, R-900, R-322 (manufacturer DuPont), micronized mica, for example, grades W1, W2, W10 (manufacturer Norwegian Talc As), silicon dioxide in the form of finely dispersed quartz flour grade A (GOST 9077-82), etc.;

[0025] - solutions of polyamide modified with urea can be used as a rheological additive;

[0026] - polyolefins can be used as a dispersant;

[0027] - polyacrylate-based additives can be used as a deaerator.

[0028] Implementation of the invention

[0029] The coating for the outer surface of the pipe, onto which marking / engraving is applied, is made of an epoxy composition based on a mixture of epoxy resin based on bisphenol A and epoxy resin based on bisphenol F. The primer (primer), in this system, is the first layer of coating, applied directly to the prepared outer surface of the pipe.

[0030] Preparation of epoxy base, curing system, epoxy composition and coating.

[0031] 1. The epoxy base is prepared by gradually mixing the components in a dissolver container at a dispersing cutter speed of 500-1500 rpm. The epoxy base contains a mixture of epoxy resins, fillers, as well as reactive organic solvents and other functional additives.

[0032] First, 10-13 wt.% xylene and 1.5-5 wt.% 2-methylpropan-1-ol are mixed in a container. In a dissolver, 8-40 wt.% of a mixture of epoxy resin based on bisphenol A and bisphenol F are mixed in a ratio of: epoxy resin based on bisphenol A : epoxy resin based on bisphenol F from 1:3 to 3:1, preferably 1:1. Then, the previously prepared Vi mixture of xylene and 2-methylpropan-1-ol is added to the resulting mixture of epoxy resins. Next, 1-3 wt.% ethylbenzene, 0.1-2.0 wt.% rheological additive, 0.5-2 wt.% dispersant and 0.1-2.0 wt.% deaerator are added to the desolver. Fillers are then added to the prepared mixture: 12-15% by weight of titanium dioxide, 12-15% by weight of micronized mica, and 20-35% by weight of silicon dioxide. Next, 0.5-1% by weight of dispersant and the remaining* mixture of xylene and 2-methylpropan-1-ol are added to the resulting mixture. Mixing is continued until a homogeneous composition is obtained.The resulting mixture is poured into a hermetically sealed container and stored until needed for epoxy coating. The preparation of an epoxy base with the stated components across the entire range is shown in Table 1.

[0033] 2. Preparation of the curing system. The curing system is prepared by mixing 22-50 wt.% of 1-1,1-diethyl-1,3-diaminopropane, 12-15 wt.% of xylene, 5-10 wt.% of 2-methylpropane-1-ol, 10-26 wt.% of benzyl alcohol, 3-10 wt.% of ethylbenzene, 6-10 wt.% of bis-(aminomethyl)benzene, 5-10 wt.% of 3-(2-aminoethylamino)propyltrimethoxysilane, 1-5 wt.% of 2-hydroxybenzoic acid in a reactor vessel until a composition of uniform consistency is obtained. Mixing is preferably carried out using a low-speed mixer at a rotation speed of 60-240 rpm. The resulting curing system is poured into a hermetically sealed container and stored until needed for epoxy coating. The preparation of the curing system with the stated components across the entire range is shown in Table 1.

[0034] 3. Preparation of the epoxy composition for the coating with marking. Preparation of the epoxy composition consists of mixing the ready-made epoxy base and the ready-made curing system manually or using a special automatic dispenser in a volume ratio of epoxy base:curing system = from 2:1 to 12:1, preferably epoxy base:curing system = 5:1. Examples of the preparation of the epoxy composition for the coating for marking are given in Table 2.

[0035] To prepare the epoxy composition, it is permissible to use the hardener obtained as described above in Section 2, or a hardener based on phenalcomines, both natural and synthetic, as well as mixtures thereof. Mixing is carried out until a homogeneous composition is obtained, preferably within 15 minutes. The prepared mixture of epoxy base and curing system must be used within two hours of the start of mixing.

[0036] 4. Obtaining coverage.

[0037] The preparation of the outer surface of the pipe is carried out as follows:

[0038] 4.1. The technical specifications determine the number of sections along the pipe (on the outer surface), as well as the dimensions of these sections. A single tubing string can accommodate from 1 to 10 annular sections for coating application, each optionally marked (engraved). The possible length of each such section ranges from 5 cm to 100 cm. For convenience, the following description describes working with one such section.

[0039] 4.2. Before applying the coating, the surface of the selected area is treated to a surface cleanliness level of at least Sa 2 i according to GOST R ISO 8501-1-2014. Surface treatment is performed using mechanical and / or abrasive blasting methods.

[0040] 4.3. Degreasing the NTC area before applying the polymer coating.

[0041] After surface treatment, the cleaned prepared surface is degreased (for example, with acetone, alcohol, alkaline detergents).

[0042] 4.4. Application of epoxy composition to obtain a coating.

[0043] 4.5. The tubing is installed on special roller stands with a rotary drive.

[0044] 4.6. Apply the prepared epoxy composition, as described in Section 3, to the prepared section of the tubing using airless or air spray. Apply the epoxy composition to the visible section of the tubing, then rotate the tubing 90 degrees and repeat the process. Continue rotating the tubing to prevent drips. Complete the polymer coating application when the wet layer thickness reaches 100-150 µm.

[0045] The polymer coating layer is applied within 10-15 minutes after degreasing. If this time is exceeded, the prepared area must be degreased again.

[0046] 4.7. Polymerization of the applied coating.

[0047] First, the epoxy coating applied to the pipe section is pre-polymerized. This step is necessary to remove solvents from the applied coating and prevent any potential drips. For this purpose, a heating element with a minimum power of 1000 W is installed in close proximity to the epoxy-coated surface. Pre-polymerization of the coating on the pipe section occurs through heat treatment for 10-15 minutes while the pipe is continuously rotating. Then, the continuous rotation mode is stopped and the tubing is switched to a mode in which the tubing rotates 90 degrees once per minute.

[0048] Full polymerization of the coating with a heating element takes from 30 minutes to 6 hours, with temperature monitoring every 15 minutes using a pyrometer. For full polymerization, the surface temperature of the polymer coating must be maintained between 130-170°C.

[0049] After the coating has fully polymerized, the heating is turned off and the tubing section is cooled in air.

[0050] 4.8 Coating quality control.

[0051] After the tubing section has completely cooled in air, the thickness of the resulting coating is measured at nine points using a thickness gauge. The average polymerized coating thickness ranges from 120 to 350 µm. Optionally, polymer coating adhesion testing is performed on specimens using the X-notch method, as well as the dielectric strength of the polymer coating and autoclave and environmental testing. For these tests, specimens are optionally painted with the same polymer composition and polymerized under the same conditions as the tubing section.

[0052] 5. Application of marking (engraving) to the coated section of the pipe.

[0053] 5.1. Encode the marking type using a 3D model or a digital / alphabetic code and enter the data into the pipe inventory system software. The applied code can be customized with the necessary information for subsequent tracking and accounting.

[0054] 5.2. A site is prepared in close proximity to the polymer-coated pipe section for the installation of laser marking equipment. Marking / engraving is performed using laser radiation, the characteristics of which are selected based on the desired task in a manner understandable to a person skilled in the art. The characteristics of the laser radiation are not the subject of this invention.

[0055] Marking involves various codes: QR codes, barcodes, numeric codes, geometric codes, etc. A marking application unit (e.g., a laser engraving system) is placed on the site. The marking parameters (laser power, marking speed, frequency, pulse duration, etc.) are adjusted based on the thickness of the polymer coating. The marking / engraving should be applied to a depth of 40-60% of the average coating thickness. The required marking / engraving is then applied to the coated pipe surface in accordance with the technical specifications. Additionally, the marking / engraving unit (with the same process parameters) applies control squares on the polymer coating, ranging in size from 5 x 5 mm to 10 x 10 mm, to monitor the marking depth.It should be noted that the parameters for laser marking are selected by specialists in this field of technology based on knowledge of the technology for applying marking / engraving on coatings based on epoxy compositions.

[0056] 6. Checking the quality of the applied marking / engraving.

[0057] 6.1. Marking depth is optionally measured in control squares using a special indicator. The depth of the main marking / engraving is estimated based on the depth of the squares.

[0058] 6.2. The ability to recognize the received marking is assessed visually and using an optical device (a special code scanner). The readability of all applied markings must be 100%.

[0059] The following are examples of how to implement this invention. While not exclusive, they clearly demonstrate the possibility of achieving the stated technical result in various embodiments.

[0060] Table 1.

[0061] Table No. 2 The resulting compositions were then applied to the prepared sections of the tubing. Each section ranged in length from 15 cm to 40 cm. The epoxy composition was applied by spraying. The tubing was then rotated 90 degrees and the process was repeated. Continuous rotation of the tubing was then started. Application of the epoxy composition was complete when a wet layer thickness of 150 µm was reached. A heating element was then used to pre-cure the epoxy composition applied to the tubing section for 15 minutes while the tubing was continuously rotated.

[0062] The coating was fully polymerized using a heating element for 6 hours, 30 minutes to 6 hours, with temperature monitoring every 15 minutes using a pyrometer. To ensure complete polymerization, the polymer coating surface temperature was maintained between 130-170°C.

[0063] After the coating had fully polymerized, the heating was turned off and the tubing section was cooled in air.

[0064] Then, using a laser engraving system, QR code markings were applied to the coated sections of the tubing. The laser power was 8 W, the line pitch was 20 lines per mm, the galvanic pair speed was 1000 mm / sec, the frequency was 100,000 Hz, and the pulse duration was 200 ns. The markings were applied at depths of 40%, 50%, and 60% of the average coating thickness.

[0065] Table 2 presents the test results of samples of metal surfaces with a laser-marked coating applied to them, made from the declared composition.

[0066] Table 3

[0067] Next, the quality of the coating and applied markings / engravings was assessed. This included the ability to recognize the markings visually and using a specialized code scanner after exposure to corrosive environments under pressure at elevated temperatures, as well as a visual assessment of the coating's durability after exposure to corrosive environments under pressure at elevated temperatures. For the studies, marked samples were cut into segments and placed in corrosive environments under the test conditions.As can be seen from Table 2, the coating with marking and the marking / engraving applied to the coating are not subject to destruction during environmental testing simulating the operation of tubing in oil production wells - testing the coating's resistance to the static effects of aggressive liquids (acids and alkalis) at elevated temperatures (keeping in 10% solutions of hydrochloric acid and sodium hydroxide at 50°C for 24 hours) according to GOST 9.403-2022 (method A) and testing the coating's resistance to corrosive environments under pressure at elevated temperatures (autoclave tests, with the test mode: 80°C, 5 MPa CO2, 5% NaCl, 24 hours) based on GOST R 58346-2019 (Appendix D) and / or NACE 0185-2006. Visual inspection of the samples revealed no coating defects. Furthermore, laser markings / engravings on the epoxy coating surface were 100% readable using code scanners.The adhesive strength of the coating by the normal peel-off method, determined in accordance with GOST 32299-2013 (ISO 4624:2002), is within the range of (13.5 - 15.0) MPa, which meets the requirements of the industry standard GOST R 58346-2019.

Claims

CLAUSES OF THE INVENTION 1. An epoxy coating composition for marking, containing an epoxy base and a curing system, wherein the epoxy base includes components in the following ratio, wt.%: a mixture of epoxy resins based on bisphenol A and bisphenol F 8-40 titanium dioxide 12-15 micronized mica 12-15 silicon dioxide 20-35 ethylbenzene 1-3 xylene 10-13 2-methylpropan-1-ol 1.5-5 rheological additive 0.1-2 dispersant 0.5-2 deaerator 0.1-2, while the ratio of epoxy resins based on bisphenol A and bisphenol F is from 1:3 to 3:1, and the curing system includes components in the following ratio, wt.%: N-1,1 - diethyl- 1 ,3 - diaminopropane 22-50 benzyl alcohol 10-26 ethylbenzene 3-10 bisaminomethylbenzene 6-10 3-(2-aminoethylamino)propyltrimethoxysilane 5-10 2-hydroxybenzoic acid 1-5 xylene 12-15 2-methylpropan-1-ol 5-10, wherein the ratio of the epoxy base to the curing system is from 2: 1 to 12:

1.

2. The epoxy composition according to claim 1, characterized in that the ratio of the epoxy base to the curing system is 5:

1.

3. An epoxy composition according to claim 1, characterized in that the epoxy resins based on bisphenol A and bisphenol F have a molecular weight of more than 700.

4. A metal substrate with an epoxy coating composition applied thereto for applying marking according to paragraph 1.

5. The metal substrate according to paragraph 4, selected from: oil country pipes and linear pipeline pipes.

6. A coating with marking based on an epoxy composition for coating for applying marking according to paragraph 1.

7. A coating with marking according to paragraph 6, characterized in that the marking is applied by laser.

8. A coating with markings according to paragraph 6, characterized in that the markings are applied to a depth of 40-60% of the average coating thickness.

Images