External coating paint for buried pipeline as well as preparation method and application of external coating paint

Abstract

The invention relates to the technical field of paint, in particular to buried pipeline outer coating paint and a preparation method thereof. The coating comprises a component A and a component B, and the mass ratio of the component A to the component B is (2.12-2.39): 1; the component A comprises the following components in parts by weight: 40-50 parts of epoxy resin, 0-5 parts of a reactive diluent, 2-3 parts of an epoxy resin toughening agent, 2-3 parts of aluminum paste, 0-20 parts of mica powder, 5-20 parts of talcum powder, 5-10 parts of pigment, 5-20 parts of glass flakes, 1-2 parts of organic bentonite, 1-2 parts of a silane coupling agent, 0.1-0.5 part of a dispersing agent, 0.1-0.5 part of a defoaming agent and 0.1-0.5 part of a flatting agent; the component B is a cardanol modified phenolic aldehyde amine curing agent; the hyperbranched modified epoxy resin cooperates with the cardanol modified phenolic aldehyde amine curing agent and the epoxy resin flexibilizer to improve the comprehensive performance of the coating; the cathodic disbonding resistance of the coating is improved through the aluminum paste; therefore, the paint which has good comprehensive performance and can meet various corrosive environments is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to an outer coating of a buried pipeline and a preparation method and application thereof. Background Art

[0002] The use of pipelines is inevitable in the process of oil extraction and transportation. The pipelines currently used are usually made of metal materials, and the buried pipelines used for oil transportation may pass through different geographical environments, including deserts, swamps, saline-alkali land, frozen soil areas, etc., and will inevitably be corroded by moisture, oxygen, various electrolytes and microorganisms in the soil during long-term use. When metal corrodes, the strength of the pipeline will be reduced, leading to safety accidents such as oil leaks. Therefore, it is particularly important to study an anti-corrosion coating for the outer coating of buried pipelines that can meet various corrosive environments.

[0003] At present, researchers have also made a lot of efforts to deal with the corrosive environment of buried pipelines, including adding zinc blocks or electric current to the pipeline to improve the anti-corrosion performance of the coating by sacrificial anode protection of the cathode; there are also methods to add toughening agents to improve the mechanical properties of the coating at low temperatures to prevent the coating from being damaged by shrinkage or external forces at low temperatures; there are also methods to improve the cross-linking degree of the coating, enhance the anti-corrosion performance and temperature resistance of the coating. However, in the prior art, for the protection method of sacrificial anode protection of the cathode, although the substrate can be made less susceptible to corrosion, under the protection of this method, once the coating is damaged in a certain area, the coating will begin to fall off under the action of electrochemistry, and cathode peeling will occur; for the addition of toughening agents to improve the mechanical properties of the coating at low temperatures, the anti-corrosion performance of the coating will be reduced to a certain extent; for the method of improving the cross-linking degree of the coating, enhancing the anti-corrosion performance and temperature resistance of the coating, this will make the mechanical properties of the coating poor and it is very easy to crack under external forces. Therefore, there is an urgent need for a buried pipeline outer coating with good comprehensive performance that can be applied to various corrosive environments. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a buried pipeline outer coating paint and its preparation method and application. The coating has good adhesion on the outer surface of the metal pipeline and has excellent mechanical properties and corrosion resistance, and can be used in various corrosive environments.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a buried pipeline outer coating material, comprising a component A and a component B, wherein the mass ratio of the component A to the component B is (2.12-2.39):1;

[0007] The component A comprises the following parts by weight: 40-50 parts of epoxy resin, 0-5 parts of active diluent, 2-3 parts of epoxy resin toughening agent, 2-3 parts of aluminum silver paste, 0-20 parts of mica powder, 5-20 parts of talc, 5-10 parts of pigment, 5-20 parts of glass flakes, 1-2 parts of organic bentonite, 1-2 parts of silane coupling agent, 0.1-0.5 parts of dispersant, 0.1-0.5 parts of defoaming agent, and 0.1-0.5 parts of leveling agent;

[0008] The component B is a cardanol-modified phenolic amine curing agent.

[0009] Preferably, the epoxy resin is a hyperbranched modified epoxy resin EV-2098.

[0010] Preferably, the active diluent is benzyl glycidyl ether 692.

[0011] Preferably, the epoxy resin toughening agent is JA-712 epoxy resin toughening agent.

[0012] Preferably, the dispersant is BYK-180 dispersant; and the defoamer is BYK-1760 defoamer.

[0013] Preferably, the leveling agent is BYK-354 leveling agent.

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

[0015] Preferably, the pigment is a mixture of titanium dioxide and organic black pigment, wherein the mass ratio of titanium dioxide to organic black pigment is (20-25): (0.5-1.5).

[0016] The present invention also provides a method for preparing an outer coating of a buried pipeline, comprising the following steps:

[0017] S1. Add epoxy resin, reactive diluent, epoxy resin toughening agent, dispersant, defoamer, leveling agent, silane coupling agent and organic bentonite into a dispersion container in sequence, and stir to pre-disperse;

[0018] S2, placing glass flakes, pigment, talcum powder, and mica powder in a dispersion container in turn, stirring and dispersing them; after being evenly dispersed, adding aluminum silver paste, and continuing to stir and disperse them to obtain prefabricated component A;

[0019] S3. Mix the component A and the component B according to the mass ratio, stir evenly, and obtain the buried pipeline outer coating.

[0020] The present invention also provides an application of a buried pipeline outer coating paint, wherein the paint is used for the buried pipeline outer coating.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention uses a hyperbranched modified epoxy resin as the main film-forming substance, and is matched with a cardanol-modified phenolic amine curing agent to prepare a coating having excellent flexibility, impact resistance, adhesion, moisture resistance and corrosion resistance. This is because the hyperbranched modified epoxy resin is formed by combining a multifunctional small molecule with a plurality of bisphenol A-type epoxy resins to form a hyperbranched macromolecule, and the numerous branches of the macromolecule lead to a large steric hindrance between molecules, which is not easy to form entanglements, and therefore has a lower viscosity. Using the hyperbranched modified epoxy resin as a film-forming substance, the coating can be prepared without adding a diluent; and also because of the particularity of the structure of the hyperbranched modified epoxy resin, when reacting with the cardanol-modified phenolic amine curing agent, the numerous branches of the hyperbranched epoxy resin molecules will intersperse with each other, making the molecular chains The segments are entangled with each other, forming a tighter network, which makes the coating have good flexibility and corrosion resistance; the use of cardanol-modified phenolic amine curing agent as a supporting curing agent is because the curing agent contains long-chain aliphatic amino groups, benzene rings and phenolic hydroxyl groups, and the coating prepared in this way has the properties of both phenolic amine and low molecular weight polyamide; the long-chain aliphatic amino groups provide the coating with excellent flexibility, impact resistance and adhesion, and the long-chain fatty chain segments are hydrophobic, which can improve the coating's resistance to humid environments, and the presence of benzene rings will make the cross-linking density higher, providing the coating with certain corrosion resistance.

[0023] (2) The present invention can also add a reactive diluent according to actual needs. The reactive diluent used in the present invention has the characteristic of participating in the film-forming reaction. If the viscosity of the system is too high, the reactive diluent can be used to replace part of the hyperbranched modified epoxy resin. In this way, the solid content of the coating can be effectively increased while ensuring that the performance of the coating is not affected, thereby optimizing the overall performance of the coating.

[0024] (3) The epoxy resin toughening agent used in the present invention is prepared by reacting a small molecule containing multiple isocyanate groups with a macromolecule having an amino group and an epoxy group at both ends. The molecules generated by this reaction have multiple side chains, and there is a certain amount of steric hindrance around a single molecule. This characteristic effectively avoids excessive increase in the viscosity of the epoxy resin toughening agent. In actual use, it can replace part of the hyperbranched modified epoxy resin to participate in the film-forming process. When this epoxy toughening agent participates in the reaction, since it has multiple long chain segments, it can construct an interpenetrating cross-linked network with the hyperbranched modified epoxy resin, thereby significantly enhancing the toughness of the coating. Even under low ambient temperature conditions, the formed coating can still withstand a certain impact force and the external force generated by the deformation of the substrate.

[0025] (4) The present invention uses aluminum silver paste, mica powder, and glass flakes as fillers because these fillers are all flaky structures, which can extend the medium penetration distance, thereby improving the medium penetration resistance of the coating. The flaky aluminum powder in the aluminum silver paste can also improve the cathode stripping resistance of the coating. This is because aluminum has a low potential and can be preferentially oxidized as an anode. After the reaction, an oxide film can be formed on the surface of the aluminum powder, which does not affect the corrosion resistance of the coating. At the same time, it can also neutralize the strong alkaline environment generated in the leaking hole due to cathode stripping, avoiding the strong alkaline environment causing a decrease in the adhesion between the coating and the substrate surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Shown is a flow chart for preparing the coating of the present invention;

[0027] Figure 2 This is a picture of the cathodic disbonding resistance test of the coating prepared from the coating obtained in Example 1;

[0028] Figure 3 This is a picture of the impact strength test of the coating prepared from the coating obtained in Example 1;

[0029] Figure 4 This is a picture of the flexibility test of the coating prepared from the coating obtained in Example 1;

[0030] Figure 5 This is a picture of the neutral salt spray resistance test of the coating prepared from the coating obtained in Example 1. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] A buried pipeline outer coating material, comprising the following components in parts by weight:

[0034] 40 parts of hyperbranched modified epoxy resin, 5 parts of benzyl glycidyl ether, 2 parts of epoxy resin toughener, 2 parts of aluminum silver paste, 16.5 parts of talc, 10 parts of pigment, 20 parts of glass flakes, 1 part of organic bentonite, 2 parts of silane coupling agent, 0.5 parts of dispersant, 0.5 parts of defoamer, 0.5 parts of leveling agent, 42 parts of cardanol modified phenolic amine curing agent;

[0035] The pigment in this embodiment is a mixture of 9.75 parts of titanium dioxide and 0.25 parts of organic black pigment;

[0036] refer to Figure 1 In this embodiment, the preparation method of the outer coating of the buried pipeline is as follows:

[0037] S1. Add hyperbranched modified epoxy resin, benzyl glycidyl ether, epoxy resin toughening agent, dispersant, defoamer, leveling agent, silane coupling agent and organic bentonite into a dispersion container in sequence, and stir to pre-disperse;

[0038] S2, placing glass flakes, pigments, and talcum powder in a dispersion container in turn, stirring and dispersing them; after being evenly dispersed, adding aluminum silver paste, and continuing to stir and disperse them to obtain prefabricated component A;

[0039] S3. According to the mass ratio, the component A is mixed with the cardanol-modified phenolic amine curing agent, and stirred evenly to obtain the buried pipeline outer coating.

[0040] Example 2

[0041] A buried pipeline outer coating material, comprising the following components in parts by weight:

[0042] 40 parts of hyperbranched modified epoxy resin, 5 parts of benzyl glycidyl ether, 3 parts of epoxy resin toughener, 2 parts of aluminum silver paste, 20 parts of talc, 10 parts of pigment, 16.6 parts of glass flakes, 1.5 parts of organic bentonite, 1 part of silane coupling agent, 0.3 parts of dispersant, 0.3 parts of defoamer, 0.3 parts of leveling agent, 43 parts of cardanol modified phenolic amine curing agent;

[0043] The pigment in this embodiment is a mixture of 9.5 parts of titanium dioxide and 0.5 parts of organic black pigment;

[0044] The preparation method of the outer coating of the buried pipeline in this embodiment is as follows:

[0045] S1. Add hyperbranched modified epoxy resin, benzyl glycidyl ether, epoxy resin toughening agent, dispersant, defoamer, leveling agent, silane coupling agent and organic bentonite into a dispersion container in sequence, and stir to pre-disperse;

[0046] S2, placing glass flakes, pigments, and talcum powder in a dispersion container in turn, stirring and dispersing them; after being evenly dispersed, adding aluminum silver paste, and continuing to stir and disperse them to obtain prefabricated component A;

[0047] S3. According to the mass ratio, the component A is mixed with the cardanol-modified phenolic amine curing agent, and stirred evenly to obtain the buried pipeline outer coating.

[0048] Example 3

[0049] 45 parts of hyperbranched modified epoxy resin, 2.5 parts of benzyl glycidyl ether, 2.5 parts of epoxy resin toughener, 3 parts of aluminum silver paste, 15 parts of mica powder, 5.3 parts of talc, 5 parts of pigment, 17.5 parts of glass flakes, 1.8 parts of organic bentonite, 1.5 parts of silane coupling agent, 0.3 parts of dispersant, 0.3 parts of defoamer, 0.3 parts of leveling agent, 44 parts of cardanol modified phenolic amine curing agent;

[0050] The pigment in this embodiment is a mixture of 9.6 parts of titanium dioxide and 0.4 parts of organic black pigment;

[0051] The preparation method of the outer coating of the buried pipeline in this embodiment is as follows:

[0052] S1. Add hyperbranched modified epoxy resin, benzyl glycidyl ether, epoxy resin toughening agent, dispersant, defoamer, leveling agent, silane coupling agent and organic bentonite into a dispersion container in sequence, and stir to pre-disperse;

[0053] S2, placing glass flakes, pigment, talcum powder and mica powder in a dispersion container in turn, stirring and dispersing them; after being evenly dispersed, adding aluminum silver paste, continuing to stir and disperse, to obtain prefabricated component A;

[0054] S3. According to the mass ratio, the component A is mixed with the cardanol-modified phenolic amine curing agent, and stirred evenly to obtain the buried pipeline outer coating.

[0055] Example 4

[0056] 45 parts of hyperbranched modified epoxy resin, 2.5 parts of benzyl glycidyl ether, 2.5 parts of epoxy resin toughener, 3 parts of aluminum silver paste, 15 parts of mica powder, 10.6 parts of talc, 7.5 parts of pigment, 10 parts of glass flakes, 1.8 parts of organic bentonite, 1.5 parts of silane coupling agent, 0.2 parts of dispersant, 0.2 parts of defoamer, 0.2 parts of leveling agent, 45 parts of cardanol modified phenolic amine curing agent;

[0057] The pigment in this embodiment is a mixture of 9.35 parts of titanium dioxide and 0.65 parts of organic black pigment;

[0058] The preparation method of the outer coating of the buried pipeline in this embodiment is as follows:

[0059] S1. Add hyperbranched modified epoxy resin, benzyl glycidyl ether, epoxy resin toughening agent, dispersant, defoamer, leveling agent, silane coupling agent and organic bentonite into a dispersion container in sequence, and stir to pre-disperse;

[0060] S2, placing glass flakes, pigment, talcum powder and mica powder in a dispersion container in turn, stirring and dispersing them; after being evenly dispersed, adding aluminum silver paste, continuing to stir and disperse, to obtain prefabricated component A;

[0061] S3. According to the mass ratio, the component A is mixed with the cardanol-modified phenolic amine curing agent, and stirred evenly to obtain the buried pipeline outer coating.

[0062] Example 5

[0063] 50 parts of hyperbranched modified epoxy resin, 3 parts of epoxy resin toughening agent, 3 parts of aluminum silver paste, 20 parts of mica powder, 5 parts of talc, 10 parts of pigment, 5 parts of glass flakes, 2 parts of organic bentonite, 1.3 parts of silane coupling agent, 0.1 parts of dispersant, 0.1 parts of defoamer, 0.1 parts of leveling agent, 46 parts of cardanol modified phenolic amine curing agent;

[0064] The pigment in this embodiment is a mixture of 9.8 parts of titanium dioxide and 0.2 parts of organic black pigment;

[0065] The preparation method of the outer coating of the buried pipeline in this embodiment is as follows:

[0066] S1. Add the hyperbranched modified epoxy resin, epoxy resin toughening agent, dispersant, defoamer, leveling agent, silane coupling agent and organic bentonite into a dispersion container in sequence, and stir to pre-disperse;

[0067] S2, placing glass flakes, pigment, talcum powder and mica powder in a dispersion container in turn, stirring and dispersing them; after being evenly dispersed, adding aluminum silver paste, continuing to stir and disperse, to obtain prefabricated component A;

[0068] S3. According to the mass ratio, the component A is mixed with the cardanol-modified phenolic amine curing agent, and stirred evenly to obtain the buried pipeline outer coating.

[0069] Example 6

[0070] 50 parts of hyperbranched modified epoxy resin, 3 parts of epoxy resin toughening agent, 3 parts of aluminum silver paste, 20 parts of mica powder, 7.4 parts of talc, 8 parts of pigment, 5 parts of glass flakes, 2 parts of organic bentonite, 1.3 parts of silane coupling agent, 0.1 parts of dispersant, 0.1 parts of defoamer, 0.1 parts of leveling agent, 47 parts of cardanol modified phenolic amine curing agent;

[0071] The pigment in this embodiment is a mixture of 9.4 parts of titanium dioxide and 0.6 parts of organic black pigment;

[0072] The preparation method of the outer coating of the buried pipeline in this embodiment is as follows:

[0073] S1. Add the hyperbranched modified epoxy resin, epoxy resin toughening agent, dispersant, defoamer, leveling agent, silane coupling agent and organic bentonite into a dispersion container in sequence, and stir to pre-disperse;

[0074] S2, placing glass flakes, pigment, talcum powder and mica powder in a dispersion container in turn, stirring and dispersing them; after being evenly dispersed, adding aluminum silver paste, continuing to stir and disperse, to obtain prefabricated component A;

[0075] S3. According to the mass ratio, the component A is mixed with the cardanol-modified phenolic amine curing agent, and stirred evenly to obtain the buried pipeline outer coating.

[0076] The coating prepared in the above embodiment is used as the outer coating of the buried pipeline, which can effectively protect the buried pipeline and extend the service life of the buried pipeline.

[0077] In the above embodiments, the hyperbranched modified epoxy resin is EV-2098 organosilicon-modified hyperbranched epoxy resin produced by Shanghai Yierfu Company;

[0078] The active diluent is benzyl glycidyl ether 692; it can also be other diluents that meet the requirements on the market;

[0079] The epoxy resin toughening agent is JA-712 epoxy resin toughening agent produced by Jiadida New Materials Co., Ltd.

[0080] The dispersant is BYK-180 dispersant produced by BYK of Germany; it may also be other dispersants meeting the requirements on the market;

[0081] The defoamer is BYK-1760 produced by BYK of Germany, or other defoamers meeting the requirements on the market;

[0082] The leveling agent is BYK-354 produced by German BYK Company, or it can be other leveling agents meeting the requirements on the market.

[0083] The silane coupling agent is a LTW adhesion promoter;

[0084] The model of the organic bentonite is HFGEL-200B organic bentonite produced by Zhejiang Fenghong, or other organic bentonite meeting the requirements on the market;

[0085] The size of the glass flakes is preferably 200 mesh;

[0086] The talcum powder is preferably talcum powder of model HS-999;

[0087] The size of the mica powder is preferably 600 mesh;

[0088] The pigments described are only for providing hiding power and the colors can be changed according to the requirements of use.

[0089] The aluminum-silver paste is preferably an aluminum-silver paste of model ZNA-110;

[0090] The cardanol-modified phenolic amine curing agent is cardanol-modified phenolic amine curing agent 6777 produced by Hangzhou Nuotu New Materials Technology Co., Ltd.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 1 is that in this comparative example, 3 parts of epoxy resin toughening agent and 17.5 parts of talcum powder are used; the rest is the same as Example 1.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 2 is that in this comparative example, 3 parts of epoxy resin toughening agent and 17.5 parts of talcum powder are used; the rest is the same as Example 2.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 3 is that in this comparative example, 1 part of aluminum silver paste and 7.3 parts of talcum powder are used; the rest is the same as Example 3.

[0097] Comparative Example 4

[0098] The difference between this comparative example and Example 4 is that in this comparative example, 4 parts of aluminum silver paste and 9.6 parts of talcum powder are used; the rest is the same as Example 4.

[0099] Comparative Example 5

[0100] The difference between this comparative example and Example 5 is that in this comparative example, the hyperbranched epoxy resin is replaced by 828 epoxy resin, and the rest is the same as Example 5.

[0101] Comparative Example 6

[0102] The difference between this comparative example and Example 6 is that in this comparative example, the cardanol-modified phenolic amine curing agent is replaced with polyamide curing agent 650, and the rest is the same as Example 6.

[0103] Table 1 Raw material composition of the outer coating of buried pipeline in Examples 1 to 6

[0104]

[0105] Table 2 Composition of the outer coating of buried pipelines in Comparative Examples 1 to 6

[0106]

[0107] In order to better illustrate the beneficial effects of the present invention, the coatings prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were subjected to performance tests:

[0108] Solid content: Determined in accordance with GB / T 1725-2007 "Determination of non-volatile matter content of paints, varnishes and plastics";

[0109] VOC content: Determined in accordance with GB / T 23986-2009 “Paints and varnishes - Determination of volatile organic compound (VOC) content - Gas chromatography”;

[0110] Flexibility: Refer to GB / T 1731-1993 "Determination of paint film flexibility" for measurement; test picture reference Figure 4 ;

[0111] Adhesion: measured with reference to ISO 21809-3-2008 "External anti-corrosion layer of buried or underwater pipelines Part 3: Field patching technology";

[0112] Impact resistance: measured in accordance with GB / T 1732-1993 "Determination of impact resistance of paint films";

[0113] Impact strength: measured with reference to ISO 21809-3-2008 "External anti-corrosion layer of buried or underwater pipelines Part 3: Field patching technology"; test pictures for reference Figure 3 ;

[0114] Bending resistance: measured with reference to ISO 21809-3-2008 "External anti-corrosion layer of buried or underwater pipelines Part 3: Field patching technology";

[0115] Salt spray resistance: refer to GB / T 1771-2007 "Determination of neutral salt spray resistance of paints and varnishes" for measurement; test pictures for reference Figure 5 ;

[0116] Resistance to moisture and heat: Determined in accordance with GB / T 1740-2007 "Determination of moisture and heat resistance of paint films";

[0117] Salt water resistance: Determined in accordance with GB / T 9274-1988 "Determination of resistance of paints and varnishes to liquid media";

[0118] Acid resistance: Determined in accordance with GB / T 9274-1988 "Determination of resistance of paints and varnishes to liquid media";

[0119] Alkali resistance: Determine with reference to GB / T 9274-1988 "Determination of resistance of paints and varnishes to liquid media";

[0120] Cathodic disbonding resistance: measured with reference to ISO 21809-3-2008 "External anti-corrosion coatings for buried or underwater pipelines Part 3: Field patching technology"; test pictures for reference Figure 2 ;

[0121] Hot water immersion resistance: measured with reference to ISO 21809-3-2008 "External anti-corrosion layer of buried or underwater pipelines Part 3: Field patching technology".

[0122] The test results are as follows:

[0123] Table 3 Performance test results of the buried pipeline outer coating obtained in Examples 1 to 6

[0124]

[0125] Table 4 Performance test results of the buried pipeline outer coating obtained in Comparative Examples 1 to 6

[0126]

[0127]

[0128] As can be seen from Table 1, the coatings prepared with the coatings obtained in Examples 1-6 have various properties that meet the requirements. The present invention improves the comprehensive properties of the coatings by using hyperbranched modified epoxy resin in conjunction with cardanol-modified phenolic amine curing agent; further improves the toughness of the coating by using hyperbranched modified epoxy resin in conjunction with epoxy resin toughening agent; further adjusts the system viscosity and low-temperature mechanical properties by using active diluent; improves the coating's resistance to medium penetration and cathode stripping performance by using flaky pigments and fillers with different oil absorption amounts and aluminum-silver paste; thereby obtaining a coating with good comprehensive performance that can meet the needs of various corrosive environments.

[0129] It can be seen from the test results of Example 1 and Comparative Examples 1-2 that in the present invention, when the content of epoxy resin toughening agent is low, the low-temperature impact resistance and bending performance of the coating do not meet the requirements, while when the content of epoxy resin toughening agent is increased, the internal crosslinking density of the coating decreases, the corrosion resistance of the coating decreases to a certain extent, and the cathode stripping resistance of the coating cannot meet the requirements.

[0130] It can be seen from the test results of Example 3 and Comparative Examples 3-4 that the addition of aluminum-silver paste has a certain effect on the stripping performance of the coating. When the aluminum-silver paste content is reduced to 1%, the aluminum powder in the aluminum-silver paste is not arranged tightly enough inside the coating, and the anti-corrosion performance and cathode stripping resistance are reduced. When the aluminum-silver paste content is increased to 4%, the aluminum-silver paste contains some solvents, which leads to a decrease in the overall solid content of the coating and does not meet the performance requirements.

[0131] From the test results of Examples 5-6 and Comparative Examples 5-6, it can be seen that when conventional resins are used in combination with cardanol-modified phenolic amine curing agents, under the premise that the anticorrosion effect is satisfied, the low-temperature bending and impact tests cannot meet the requirements. This is because the molecular weight of the conventional resin used is relatively small, resulting in a relatively close spatial distance between groups, a relatively large rigidity of the coating, and a certain influence of the mechanical properties of the coating on the resistance to cathodic stripping, which is reflected in the expansion of the affected area when the coating is stripped. When hyperbranched modified epoxy resins are used in combination with conventional epoxy resin curing agents, the acid resistance, cathodic stripping resistance and low-temperature mechanical properties of the coating are relatively poor. This is because conventional epoxy resin curing agents are low-molecular polyamides, and their cross-linking density is relatively limited after reacting with the resin, and their anticorrosion performance and cathodic stripping performance are reduced, and the amide bond is easily decomposed in an acidic environment.

[0132] The specific embodiments of the present invention enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0133] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A buried pipeline outer coating, characterized in that: It comprises component A and component B, wherein the mass ratio of component A to component B is (2.12-2.39):1; The component A comprises the following parts by weight: 40-50 parts of epoxy resin, 0-5 parts of active diluent, 2-3 parts of epoxy resin toughening agent, 2-3 parts of aluminum silver paste, 0-20 parts of mica powder, 5-20 parts of talc, 5-10 parts of pigment, 5-20 parts of glass flakes, 1-2 parts of organic bentonite, 1-2 parts of silane coupling agent, 0.1-0.5 parts of dispersant, 0.1-0.5 parts of defoaming agent, and 0.1-0.5 parts of leveling agent; The component B is a cardanol-modified phenolic amine curing agent.

2. The buried pipeline outer coating material according to claim 1, characterized in that: The epoxy resin is hyperbranched modified epoxy resin EV-2098.

3. The buried pipeline outer coating material according to claim 1, characterized in that: The active diluent is benzyl glycidyl ether 692.

4. The buried pipeline outer coating material according to claim 1, characterized in that: The epoxy resin toughening agent is JA-712 epoxy resin toughening agent.

5. The buried pipeline outer coating material according to claim 1, characterized in that: The dispersant is BYK-180 dispersant; and the defoamer is BYK-1760 defoamer.

6. The buried pipeline outer coating material according to claim 1, characterized in that: The leveling agent is BYK-354 leveling agent.

7. The buried pipeline outer coating material according to claim 1, characterized in that: The silane coupling agent is a LTW adhesion promoter.

8. The buried pipeline outer coating material according to claim 1, characterized in that: The pigment is a mixture of titanium dioxide and organic black pigment, wherein the mass ratio of titanium dioxide to organic black pigment is (20-25): (0.5-1.5).

9. A method for preparing an outer coating material for a buried pipeline according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Add epoxy resin, reactive diluent, epoxy resin toughening agent, dispersant, defoamer, leveling agent, silane coupling agent and organic bentonite into a dispersion container in sequence, and stir to pre-disperse; S2, placing glass flakes, pigment, talcum powder, and mica powder into a dispersion container in sequence, and stirring and dispersing them; After being evenly dispersed, aluminum silver paste is added and the mixture is stirred and dispersed continuously to obtain prefabricated component A; S3. Mix the component A and the component B according to the mass ratio, stir evenly, and obtain the buried pipeline outer coating.

10. An application of an outer coating material for a buried pipeline, characterized in that: The coating is prepared according to claim 9, and is used for the outer coating of a buried pipeline.

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