Protective coating for fuel storage and transportation cabin and preparation method of protective coating

Abstract

The invention provides a protective coating for a fuel storage and transportation cabin and a preparation method thereof, the protective coating comprises a primer layer, and the primer layer comprises a component A and a component B, the component A is prepared from the following raw materials in parts by weight: 20 to 40 parts of phosphorylated-sulfur heterocyclic modified epoxy resin, 0.1 to 1 part of dispersing agent, 0.1 to 1 part of flatting agent, 0.1 to 1 part of defoaming agent, 0 to 10 parts of n-butyl alcohol, 0 to 10 parts of xylene, 10 to 15 parts of zinc phosphate, 0.5 to 1.0 part of thixotropic agent, 10 to 15 parts of flaky filler, 20 to 35 parts of talcum powder, 5 to 10 parts of barite powder and 3 to 10 parts of titanium dioxide; the component B is prepared from the following raw materials in parts by weight: 99 to 100 parts of amino resin and 0.3 to 0.8 part of a catalyst. Phosphorylation-sulfur heterocycle is utilized to modify epoxy resin, a phosphating group (P-O-C) is generated, the lipophobicity is increased, an intrinsic anti-swelling network is constructed based on a sulfur / phosphorus atom covalent bonding epoxy skeleton, and by utilizing the three-dimensional shielding effect of phosphorus atoms and the high-density cross-linking characteristic of thioether bonds, the anti-swelling performance of the epoxy resin is improved. Fuel oil permeation channels are blocked from the molecular level, pollutant dissolution is inhibited, and it is ensured that the coating has good soaking resistance to fuel oil.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a protective coating for fuel storage and transportation tanks and its preparation method. Background Technology

[0002] Protective coatings for aviation fuel storage and transportation facilities face systemic technical challenges: In terms of corrosion control, existing systems struggle to simultaneously resist electrochemical corrosion induced by microbial metabolites and swelling stress corrosion caused by fuel organic components. In particular, the localized corrosion cells formed by fungal growth at the oil-water interface significantly accelerate coating failure. In terms of contamination control, traditional protective materials (such as polyurethane-epoxy hybrid coatings), as well as more basic unmodified epoxy coatings and phenolic epoxy coatings with slightly better temperature resistance, suffer from limitations due to the presence of hydrolyzable groups in their polymer chains (such as hydrophilic groups from residual amine curing agents in epoxy systems and hydroxymethyl groups in phenolic epoxy). Containing easily migratable components such as unreacted monomers and low molecular weight curing agent fragments, long-term contact with fuel not only leads to the continuous dissolution of small molecule organic matter, causing an uncontrollable increase in fuel gum content, but also the chemical aging of the coating itself in the fuel environment (such as oxidation and chain scission of the epoxy main chain and hydrolysis of phenolic resin) and microbial degradation will continuously generate new polar small molecule pollutants. In addition, the accumulation of extracellular polymers (EPS) formed by microorganisms at the interface, the synergistic effect of this multiple pollution sources makes it impossible for unmodified epoxy and phenolic epoxy coatings to effectively control the fuel gum content, thereby affecting crude oil quality and even endangering the safety of aircraft engines.

[0003] CN109836975A discloses an anti-corrosion conductive coating, its preparation method, and its application. The coating is obtained by uniformly mixing resin, solvent, and conductive filler, followed by grinding. By selecting a polyaryletherketone resin with excellent resistance to extreme environments such as strong acids, strong alkalis, and high temperatures, the coating achieves adaptability to extreme operating environments. Simultaneously, the selection of suitable conductive fillers maintains good conductivity, ensuring that the coating retains good conductivity even in extreme environments, greatly expanding the application scenarios of conductive coatings. However, long-term use of anti-corrosion conductive coatings on the inner and outer surfaces of fuel tanks and aircraft fuel containers in aerospace applications can cause the coating to swell and fail. Furthermore, the coating cannot effectively prevent fuel immersion, thus affecting fuel quality. Summary of the Invention

[0004] In view of this, the present invention aims to provide a protective coating for fuel storage and transportation tanks and its preparation method, so as to solve the problems that existing coatings are difficult to function in a fuel environment for a long time and are not resistant to fuel immersion.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] This invention proposes a protective coating for fuel storage and transportation tanks. The protective coating includes a primer layer, which comprises component A and component B. Component A comprises the following raw materials in parts by weight: 20-40 parts of phosphorylated-sulfur heterocyclic modified epoxy resin, 0.1-1 parts of dispersant, 0.1-1 parts of leveling agent, 0.1-1 parts of defoamer, 0-10 parts of n-butanol, 0-10 parts of xylene, 10-15 parts of zinc phosphate, 0.5-1.0 parts of thixotropic agent, 10-15 parts of flake filler, 20-35 parts of talc, 5-10 parts of barite powder, and 3-10 parts of titanium dioxide. Component B comprises the following raw materials in parts by weight: 99-100 parts of amino resin and 0.3-0.8 parts of catalyst.

[0007] Furthermore, the phosphorylated-sulfur heterocyclic modified epoxy resin is selected at 20 or 40 parts. The dispersant is selected at 0.1 or 1 part. The leveling agent is selected at 0.1 or 1 part. The defoamer is selected at 0.1 or 1 part. The n-butanol is selected at 0 or 10 parts. The xylene is selected at 0 or 10 parts. The zinc phosphate is selected at 10 or 15 parts. The thixotropic agent is selected at 0.5 or 1.0 part. The flake filler is selected at 10 or 15 parts. The talc is selected at 20 or 35 parts. The barite powder is selected at 5 or 10 parts. The titanium dioxide is selected at 3 or 10 parts. The amino resin is selected at 99-100 parts. The catalyst is selected at 0.3 or 0.8 parts.

[0008] Furthermore, the protective coating also includes a sealing layer, which comprises component A and component B. Component A comprises the following raw materials in parts by weight: 85-89 parts of polysulfide rubber, 10-15 parts of conductive mica powder, 0.1-1 parts of rheology modifier, and 0.1-5 parts of fumed silica; component B comprises 100 parts of dibutyltin dilaurate.

[0009] Furthermore, the polysulfide rubber is selected in the form of 85 or 89 parts, the conductive mica powder is selected in the form of 10 or 15 parts, the rheology modifier is selected in the form of 0.1 or 1 part, and the fumed silica is selected in the form of 0.1 or 5 parts.

[0010] Furthermore, the preparation method of the phosphorylated-sulfur heterocyclic modified epoxy resin includes the following steps:

[0011] α-phosphorylation:

[0012] 800-1000 parts of bisphenol A type epoxy resin (epoxy equivalent EEW=185 g / eq) were reacted with 654-901 parts of a compound phosphoric acid system under nitrogen protection. The reaction endpoint was controlled with acid value ≤5 mg KOH / g.

[0013] b-sulfur heterocyclic grafting:

[0014] Add 0.18 mol / epoxy equivalent of 2-mercaptobenzothiazole to the product of step a and react at 78-85 °C for 2.5-3.5 h.

[0015] Furthermore, in step a, the compound phosphoric acid system comprises 441-607 parts of H3PO4 and 213-294 parts of phenylphosphonic acid; the bisphenol A type epoxy resin and the compound phosphoric acid system are reacted at 58-62°C under nitrogen protection for 1.5-2.5 hours.

[0016] Furthermore, for component A, the dispersant is selected from at least one of BYK-110 and UK710S; the leveling agent is selected from at least one of BIK-320 and UK384S; the defoamer is selected from at least one of UK272S and BYK-A530; the thixotropic agent is selected from polyamide wax; and the flake filler is selected from at least one of glass flakes, basalt flakes, and mica powder.

[0017] Furthermore, for component B, the amino resin is selected from CYMEL 1130, and the catalyst is selected from DMP-30.

[0018] Furthermore, for component A, the molecular weight of the polysulfide rubber is 2500~3000, the conductive mica powder is selected from BC-C, the rheology modifier is selected from at least one of BYK-405, BYK-410, and BYK-411, and the fumed silica is M-5.

[0019] Furthermore, the polysulfide rubber is Thiokol® LP-32, a polysulfide rubber with a molecular weight of 2500.

[0020] Furthermore, the ratio of component A to component B is 10-15:1, and the amount of component B is 0.3-0.8% of component A.

[0021] The present invention also proposes a method for preparing the above-mentioned protective coating, comprising the following steps:

[0022] S1. Preparation of component A of the primer layer:

[0023] Add phosphorylated-sulfur heterocyclic modified epoxy resin, dispersant, leveling agent, defoamer, n-butanol and xylene to the mixture and disperse at 800~1500 r / min for 10~15 min;

[0024] Continue to add zinc phosphate, flake filler, titanium dioxide, talc, and barite powder, and disperse at 800~1500 r / min until the fineness is ≤100μm;

[0025] Next, add the thixotropic agent, heat to 50~65℃, and disperse at 800~1500r / min for 10~20min;

[0026] Component A was obtained through filtration and packaging.

[0027] S2. Preparation of component B of the primer layer:

[0028] Add amino resin and catalyst, disperse at 800~1500 r / min for 10~30 min, filter and package to obtain component B;

[0029] S3. Preparation of component A of the sealing layer:

[0030] Add polysulfide rubber, conductive mica powder, rheology modifier, and fumed silica to the mixture, disperse at 800~1500 r / min for 20~30 min, filter and package to obtain component A;

[0031] Before use, components A and B will be mixed to obtain a primer layer, and components A and B will be mixed to obtain a sealing layer. During application, the primer layer will be applied to the sample first, followed by the sealing layer.

[0032] Furthermore, the coating thickness of the primer layer is 200~300μm, and the coating thickness of the sealing layer is 100~120μm.

[0033] Furthermore, the coating thickness of the primer layer is 200μm or 300μm, and the coating thickness of the sealing layer is 100μm.

[0034] In this invention, firstly, an intrinsic anti-swelling network is constructed based on a sulfur / phosphorus covalently bonded epoxy framework. The stereo shielding effect of phosphorus atoms and the high-density cross-linking characteristics of thioether bonds are utilized to block fuel permeation channels and inhibit the dissolution of pollutants at the molecular level.

[0035] Secondly, through the design of a functional layered composite system, while constructing a dense chemical protective barrier in the primer layer, a polysulfide rubber sealing layer is introduced to physically fill microscopic defects, forming a dual protection mechanism of static protection and dynamic impermeability.

[0036] Finally, by using a compound catalytic low-temperature curing process, and with the synergistic activation effect of amines and metal catalysts, the epoxy network was efficiently constructed under a wide temperature range.

[0037] Compared with existing technologies, the protective coating for fuel storage and transportation tanks and its preparation method described in this invention have the following advantages:

[0038] (1) In the phosphorylation reaction, the P-OH group and epoxy group in the compound phosphoric acid system react to generate phosphoric acid group (POC), which is beneficial to increase oleophobicity. In the thioheterocyclic grafting reaction, the thiol group (-SH) of 2-mercaptobenzothiazole undergoes a ring-opening addition reaction with the epoxy group to form a stable thioether bond (CSC), which is beneficial to increase the crosslinking density of the coating and can form a thermodynamic barrier layer to ensure that the coating has good anti-soaking properties against fuel.

[0039] (2) The polysulfide rubber in the sealing layer provides physical damage repair capabilities through sulfur exchange reaction, while its degradation product, benzothiazole disulfide, acts as a long-lasting antibacterial agent, enabling simultaneous "repair + protection". The sulfur heterocycles in the primer layer can inhibit bacteria, and the degradation product of polysulfide rubber in the sealing layer, benzothiazole disulfide, can also inhibit bacteria. Together, they reduce the impact of microbial metabolites on fuel.

[0040] (3) The primer layer is a rigid material with a small free volume, which can inhibit the seepage of leachate. The sealing layer is a flexible material. The combination of the two can dynamically inhibit the swelling of the coating, prevent the seepage of small molecules, inhibit the growth of microorganisms, reduce the rate of microbial corrosion, and reduce adhesive pollution.

[0041] (4) The primer layer and the sealing layer work together to achieve static protection and dynamic impermeability through the synergistic effect of chemical protection and physical barrier, breaking through the limitations of a single coating and designing a "chemical-physical" dual-effect barrier structure. In addition, the primer layer achieves cathodic protection of the metal substrate through zinc phosphate filler, while the polysulfide sealing layer extends the length of the penetration path through molecular chain entanglement and dynamically fills the micro-defects of the primer layer, extending the fuel penetration path. The physical superposition of the two achieves the complementary functions of static protection and dynamic impermeability. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.

[0043] A protective coating for fuel storage and transportation tanks includes a primer layer, which comprises component A and component B. Component A comprises the following raw materials in parts by weight: 20-40 parts of phosphorylated-sulfur heterocyclic modified epoxy resin, 0.1-1 parts of dispersant, 0.1-1 parts of leveling agent, 0.1-1 parts of defoamer, 0-10 parts of n-butanol, 0-10 parts of xylene, 10-15 parts of zinc phosphate, 0.5-1.0 parts of thixotropic agent, 10-15 parts of flake filler, 20-35 parts of talc, 5-10 parts of barite powder, and 3-10 parts of titanium dioxide. Component B comprises the following raw materials in parts by weight: 99-100 parts of amino resin and 0.3-0.8 parts of catalyst.

[0044] The preparation method of the phosphorylated-sulfide heterocyclic modified epoxy resin includes the following steps:

[0045] α-phosphorylation:

[0046] 800-1000 parts of bisphenol A type epoxy resin (epoxy equivalent EEW=185 g / eq) were reacted with 654-901 parts of a compound phosphoric acid system under nitrogen protection. The reaction endpoint was controlled with acid value ≤5 mg KOH / g.

[0047] b-sulfur heterocyclic grafting:

[0048] Add 0.18 mol / epoxy equivalent of 2-mercaptobenzothiazole to the product of step a and react at 78-85 °C for 2.5-3.5 h.

[0049] In the phosphorylation reaction, the P-OH groups and epoxy groups in the compound phosphoric acid system react to generate phosphating groups (POC), which is beneficial for increasing oleophobicity and achieving a contact angle >95°. In the thioheterocyclic grafting reaction, the thiol group (-SH) of 2-mercaptobenzothiazole undergoes a ring-opening addition reaction with the epoxy group to form a stable thioether bond (CSC), which is beneficial for increasing the crosslinking density of the coating. The solubility parameter difference between the thioether bond and the fuel alkane reaches 8.5 (J / cm³). 3 ) 0.5 It can form a thermodynamic barrier layer, ensuring that the coating has good resistance to fuel immersion.

[0050] The synergistic construction of a sulfur-phosphorus molecular network provides both an oleophobic barrier and a dense cross-linked network. Phosphorylation introduces polar POC bonds, while simultaneously utilizing sulfur heterocycles to construct a highly cross-linked network (cross-linking density up to 285 g / mol). The covalent bonding of these two components forms a dense, three-dimensional structure with small pores, synergistically blocking fuel permeation channels and inhibiting contaminant dissolution at the molecular scale, thus solving the problem of traditional coatings' tendency to swell and fail. The phosphorylated-sulfur heterocycle-modified epoxy resin and zinc phosphate in the primer layer achieve both chemical and cathodic protection.

[0051] As a preferred example of the present invention, the protective coating further includes a sealing layer, the sealing layer comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 85-89 parts of polysulfide rubber, 10-15 parts of conductive mica powder, 0.1-1 parts of rheology modifier and 0.1-5 parts of fumed silica; and component B comprises 100 parts of dibutyltin dilaurate.

[0052] The sulfur exchange reaction of polysulfide rubber is as follows (dynamic covalent chemistry):

[0053]

[0054] This invention provides physical damage repair capabilities through the sulfur exchange reaction of the polysulfide rubber in the sealing layer. Simultaneously, its degradation product, benzothiazole disulfide, acts as a long-lasting antibacterial agent, achieving simultaneous "repair + protection." The sulfur heterocycles in the primer layer and the benzothiazole disulfide degradation product in the sealing layer also inhibit bacteria; together, they reduce the impact of microbial metabolites on fuel. Furthermore, the primer layer, being a rigid material with a small free volume, inhibits the seepage of leachates, while the sealing layer, being a flexible material, works in combination to dynamically inhibit coating swelling, prevent the seepage of small molecules, suppress microbial growth, reduce the rate of microbial corrosion, and decrease gum contamination.

[0055] The primer and sealant layers work together to achieve both static protection and dynamic impermeability through the synergistic effect of chemical protection and physical barriers, overcoming the limitations of single coatings and designing a dual-effect "chemical-physical" barrier structure. The primer layer constructs a dense chemical protective barrier to achieve static sealing, while the polysulfide rubber in the sealant layer dynamically fills microscopic defects, forming an adaptive deformation capability. The two layers work together at the interface to construct a dual guarantee of "static rigid protection + dynamic flexible impermeability," significantly improving the reliability of protection under complex working conditions. In addition, the primer layer achieves cathodic protection of the metal substrate through zinc phosphate filler, while the polysulfide sealant layer extends the permeation path length through molecular chain entanglement and dynamically fills the micro-defects in the primer layer, extending the fuel permeation path. The physical superposition of the two layers achieves complementary functions of static protection and dynamic impermeability.

[0056] The protective coating of this invention achieves the following technical effects through a three-stage synergy: molecular barrier of the primer layer, adsorption and oil absorption of the sealing layer, and dynamic repair of the sealing layer. This simultaneously solves the three major problems of swelling, gum contamination, and microbial corrosion, resulting in the following: low fuel permeability and reduced microbial corrosion rate; low gum content and improved pollution control; long-lasting protection, suitable for long-term corrosion resistance, and applicable to fuel storage and transportation scenarios such as ships, aviation, and storage tanks.

[0057] For component A, the dispersant is selected from at least one of BYK-110 and UK710S; the leveling agent is selected from at least one of BIK-320 and UK384S; the defoamer is selected from at least one of UK272S and BYK-A530; the thixotropic agent is selected from polyamide wax; and the flake filler is selected from at least one of glass flakes, basalt flakes, and mica powder.

[0058] For component B, the amino resin is selected from CYMEL 1130, and the catalyst is selected from DMP-30. For component A, the polysulfide rubber has a molecular weight of 2500-3000, the conductive mica powder is selected from BC-C, the rheology modifier is selected from at least one of BYK-405, BYK-410, and BYK-411, and the fumed silica is M-5.

[0059] DMP-30, when used as a catalyst in combination with amino resins and organotin compounds, enables efficient curing over a wide temperature range of 5~40℃.

[0060] When using the product, the ratio of component A to component B is 10 to 15:1, and the amount of component B is 0.3 to 0.8% of that of component A.

[0061] Experimental Example 1: Preparation of Phosphorylated-Thioheterocyclic Modified Epoxy Resin

[0062] α-phosphorylation:

[0063] 800g of bisphenol A type epoxy resin (epoxy equivalent EEW = 185 g / eq) and 654g of compound phosphoric acid system were reacted at 58℃ under nitrogen protection for 1.5h. The reaction endpoint was controlled with acidity value ≤ 5 mg KOH / g. The compound phosphoric acid system included 441g of H3PO4 and 213g of phenylphosphonic acid.

[0064] b-sulfur heterocyclic grafting:

[0065] 2-Mercaptobenzothiazole (0.18 mol / epoxy equivalent) was added to the product of step a, and the reaction was carried out at 78 °C for 2.5 h.

[0066] Experimental Example 2: Preparation of Phosphorylated-Thioheterocyclic Modified Epoxy Resin

[0067] α-phosphorylation:

[0068] 1000g of bisphenol A type epoxy resin (epoxy equivalent EEW = 185 g / eq) and 901g of a compound phosphoric acid system were reacted at 62℃ under nitrogen protection for 2.5h, and the reaction endpoint was controlled with an acid value ≤ 5 mg KOH / g; the compound phosphoric acid system included 607g of H3PO4 and 294g of phenylphosphonic acid.

[0069] b-sulfur heterocyclic grafting:

[0070] 2-Mercaptobenzothiazole (0.18 mol / epoxy equivalent) was added to the product of step a, and the mixture was reacted at 85 °C for 3.5 h.

[0071] Weigh each component according to the components and dosage of the primer layer in Table 1 and the components and dosage of the sealant layer in Table 2. The units are all g.

[0072] Table 1

[0073]

[0074]

[0075] Table 2

[0076]

[0077] The phosphorylated-sulfur heterocyclic modified epoxy resin used in Sample 1 was prepared in Experimental Example 1. The dispersant used was BYK-110, the leveling agent was BIK-320, the defoamer was UK272S, and the flake filler was sericite powder. The phosphorylated-sulfur heterocyclic modified epoxy resin used in Sample 2 was prepared in Experimental Example 1. The dispersant used was UK710S, the leveling agent was UK384S, the defoamer was BYK-A530, and the flake filler was glass flakes. The phosphorylated-sulfur heterocyclic modified epoxy resin used in Sample 3 was prepared in Experimental Example 2. The dispersant used was UK710S, the leveling agent was UK384S, the defoamer was BYK-A530, and the flake filler was glass flakes.

[0078] The rheology modifier used in Sample 4 was BYK-405, the rheology modifier used in Sample 5 was BYK-410, and the rheology modifier used in Sample 6 was BYK-411. The molecular weight of the polysulfide rubber Thiokol® LP-32 used in Samples 4 to 6 was 2500.

[0079] Sample 1

[0080] Weigh each component of component A and component B according to sample 1 in Table 1.

[0081] Preparation of component A of the primer layer: Phosphorylated-sulfur heterocyclic modified epoxy resin, dispersant, leveling agent, defoamer, n-butanol, and xylene were added and mixed, and dispersed at 800 r / min for 10 min; zinc phosphate, flake filler, titanium dioxide, talc, and barite powder were added, and dispersed at 800 r / min until the fineness was ≤100 μm; then thixotropic agent was added, the temperature was raised to 50℃, and dispersed at 800 r / min for 10 min; the mixture was filtered and packaged to obtain component A.

[0082] Preparation of component B of primer layer: Add amino resin and DMP-30, disperse at 800 r / min for 10 min, filter and package to obtain component B.

[0083] The primer layer is obtained by thoroughly mixing component A and component B at a mass ratio of 13.5:1.

[0084] Sample 2

[0085] Weigh each component of component A and component B according to sample 2 in Table 1.

[0086] Preparation of component A of the primer layer: Phosphorylated-sulfur heterocyclic modified epoxy resin, dispersant, leveling agent, defoamer, n-butanol, and xylene were added and mixed, and dispersed at 1000 r / min for 13 min; zinc phosphate, flake filler, titanium dioxide, talc, and barite powder were added, and dispersed at 1200 r / min until the fineness was ≤100 μm; then thixotropic agent was added, the temperature was raised to 55℃, and dispersed at 1000 r / min for 15 min; the mixture was filtered and packaged to obtain component A.

[0087] Preparation of component B of primer layer: Add amino resin and catalyst, disperse at 1200 r / min for 20 min, filter and package to obtain component B.

[0088] The primer layer is obtained by thoroughly mixing component A and component B at a mass ratio of 15:1.

[0089] Sample 3

[0090] Weigh each component of component A and component B according to sample 3 in Table 1.

[0091] Preparation of component A of the primer layer: Phosphorylated-sulfur heterocyclic modified epoxy resin, dispersant, leveling agent, defoamer, n-butanol, and xylene were added and mixed, and dispersed at 1500 r / min for 15 min; zinc phosphate, flake filler, titanium dioxide, talc, and barite powder were added, and dispersed at 1500 r / min until the fineness was ≤100 μm; then a thixotropic agent was added, the temperature was raised to 65℃, and dispersed at 1100 r / min for 20 min; the mixture was filtered and packaged to obtain component A.

[0092] Preparation of component B of primer layer: Add amino resin and catalyst, disperse at 1500 r / min for 30 min, filter and package to obtain component B.

[0093] The primer layer is obtained by thoroughly mixing component A and component B at a mass ratio of 10:1.

[0094] Sample 4

[0095] Weigh each component of component A and component B according to sample 4 in Table 2.

[0096] Preparation of component A of the sealing layer: Polysulfide rubber, conductive mica powder, rheology modifier, and fumed silica were added and mixed, dispersed at 800 r / min for 20 min, filtered, and packaged to obtain component A. Component A and component B were thoroughly mixed to obtain the sealing layer, with the amount of component B being 0.3% of the amount of component A.

[0097] Sample 5

[0098] Weigh each component of component A and component B according to sample 5 in Table 2.

[0099] Preparation of component A of the sealing layer: Polysulfide rubber, conductive mica powder, rheology modifier, and fumed silica were added and mixed, dispersed at 1000 r / min for 25 min, filtered, and packaged to obtain component A. Component A and component B were thoroughly mixed to obtain the sealing layer, with the amount of component B being 0.5% of the amount of component A.

[0100] Sample 6

[0101] Weigh each component of component A and component B according to sample 6 in Table 2.

[0102] Preparation of component A of the sealing layer: Polysulfide rubber, conductive mica powder, rheology modifier, and fumed silica were added and mixed, dispersed at 1500 r / min for 30 min, filtered, and packaged to obtain component A. Component A and component B were thoroughly mixed to obtain the sealing layer, with the amount of component B being 0.8% of the amount of component A.

[0103] Weigh each component according to the components and dosage in Table 3 below. The unit is g.

[0104] Table 3

[0105]

[0106] The dispersant, leveling agent, defoamer, thixotropic agent, and flake filler used in the above comparative samples 1-3 are the same as those in sample 2, and the preparation method of the primer layer is also the same as that in sample 2.

[0107] Example 1

[0108] The primer layer of sample 1 and the sealing layer of sample 4 were sequentially coated onto the test specimens. The primer layer had a coating thickness of 200 μm, and the sealing layer had a coating thickness of 100 μm. Several test specimens were prepared by sealing the edges and cured for 7 days before relevant tests were conducted.

[0109] Example 2

[0110] The primer layer of sample 2 and the sealing layer of sample 5 were sequentially coated onto the test specimens. The primer layer had a coating thickness of 200 μm, and the sealing layer had a coating thickness of 100 μm. Several test specimens were prepared by sealing the edges and cured for 7 days before relevant tests were conducted.

[0111] Example 3

[0112] The primer layer of sample 3 and the sealing layer of sample 6 were sequentially coated onto the test specimens. The primer layer had a coating thickness of 200 μm, and the sealing layer had a coating thickness of 100 μm. Several test specimens were prepared by sealing the edges and cured for 7 days before relevant tests were conducted.

[0113] Comparative Example 1

[0114] The primer layer of control sample 1 and the sealing layer of sample 5 were sequentially coated onto the sample. The primer layer had a coating thickness of 200 μm, and the sealing layer had a coating thickness of 100 μm. Several test samples were prepared by sealing the edges and cured for 7 days before relevant tests were conducted.

[0115] Comparative Example 2

[0116] The primer layer of control sample 2 was applied to the sample, with a coating thickness of 200 μm. Several test samples were prepared by sealing the edges and curing for 7 days before relevant tests were conducted.

[0117] Comparative Example 3

[0118] The primer layer of control sample 3 was applied to the sample, with a thickness of 200 μm. Several test samples were prepared by sealing the edges and curing for 7 days before relevant tests were conducted.

[0119] The coatings prepared in Examples 1-3 and Comparative Examples 1-3 were applied to test samples to obtain test samples. The quality of the fuel and the anti-corrosion performance of the samples were tested. The results are shown in Table 4.

[0120] Table 4

[0121]

[0122] As shown in Table 4, the test samples coated with the protective coatings of Examples 1-3 of this invention, after immersion in aviation kerosene and organic solvents (a mixture of isooctane and toluene at a volume ratio of 7:3), showed a gum content of less than 7 mg / 100L in both the kerosene and organic solvents, meeting the EI standard requirements. Lower gum content results in less impact on the oil quality; EI 1541 specifies that the gum content must be less than 7 mg / 100L. Besides having no impact on the quality of aviation kerosene, the coatings also exhibit excellent resistance to aviation kerosene immersion, salt spray, and oil-water resistance. Using the protective coatings of this invention, aviation kerosene storage equipment can be effectively protected, while also providing excellent sealing performance.

[0123] Comparative Examples 1 and 3 used bisphenol F epoxy resin instead of phosphorylated-sulfur heterocyclic modified epoxy resin. This not only increases the gum content, which can have adverse effects on oil products, but also results in poor oil and water resistance. Compared to the ordinary epoxy resins used in Comparative Examples 1 and 3, the phosphorylated-sulfur heterocyclic dual-modified epoxy resin primers used in Examples 1-3 can effectively block fuel penetration and oil-water interface penetration, and have better shielding performance against various small molecule compounds.

[0124] Comparative Example 3 did not contain zinc phosphate, had a high content of colloids, and a low impedance, which was detrimental to the cathodic protection of the metal substrate.

[0125] Comparative Examples 2 and 3 only have a primer layer and do not include a sealing layer. The loss of either the primer or the sealing layer significantly reduces the protective effect and the protection against oil. Compared to Comparative Examples 2 and 3, the phosphorylated-sulfur heterocyclic dual-modified epoxy resin primer + rubber sealing layer in Examples 1-3 effectively constructs a composite barrier mechanism of chemical protective primer and physical impermeable oleophobic self-healing sealing layer, thereby improving the protective effect on the substrate and achieving low contamination of oil. This invention utilizes the synergistic protective effect of the primer layer (containing phosphorylated-sulfur heterocyclic dual-modified epoxy resin, amino resin, and zinc phosphate filler) and the sealing layer (Thiokol® LP-32 polysulfide rubber + organotin crosslinking agent) to provide excellent protection for fuel oil storage and transportation tank equipment, while having no significant impact on the quality of the fuel oil, thus solving the problems of swelling corrosion and fuel oil contamination in storage and transportation facilities.

[0126] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A protective coating for fuel storage and transportation tanks, characterized in that, The protective coating includes a primer layer, which comprises component A and component B. Component A comprises the following raw materials in parts by weight: 20-40 parts of phosphorylated-sulfur heterocyclic modified epoxy resin, 0.1-1 parts of dispersant, 0.1-1 parts of leveling agent, 0.1-1 parts of defoamer, 0-10 parts of n-butanol, 0-10 parts of xylene, 10-15 parts of zinc phosphate, 0.5-1.0 parts of thixotropic agent, 10-15 parts of flake filler, 20-35 parts of talc, 5-10 parts of barite powder, and 3-10 parts of titanium dioxide. Component B comprises the following raw materials in parts by weight: 99-100 parts of amino resin and 0.3-0.8 parts of catalyst.

2. The protective coating according to claim 1, characterized in that, The protective coating also includes a sealing layer, which comprises component A and component B. Component A comprises the following raw materials in parts by weight: 85-89 parts of polysulfide rubber, 10-15 parts of conductive mica powder, 0.1-1 parts of rheology modifier, and 0.1-5 parts of fumed silica; component B comprises 100 parts of dibutyltin dilaurate.

3. The protective coating according to claim 1, characterized in that, The preparation method of the phosphorylated-thioheterocyclic modified epoxy resin includes the following steps: α-phosphorylation: 800-1000 parts of bisphenol A type epoxy resin (epoxy equivalent EEW=185 g / eq) were reacted with 654-901 parts of a compound phosphoric acid system under nitrogen protection. The reaction endpoint was controlled with acid value ≤5 mg KOH / g. b-sulfur heterocyclic grafting: Add 0.18 mol / epoxy equivalent of 2-mercaptobenzothiazole to the product of step a and react at 78-85 °C for 2.5-3.5 h.

4. The protective coating according to claim 3, characterized in that, In step a, the compound phosphoric acid system comprises 441-607 parts of H3PO4 and 213-294 parts of phenylphosphonic acid; the bisphenol A epoxy resin and the compound phosphoric acid system are reacted at 58-62°C under nitrogen protection for 1.5-2.5 hours.

5. The protective coating according to claim 1, characterized in that, For component A, the dispersant is selected from at least one of BYK-110 and UK710S; the leveling agent is selected from at least one of BIK-320 and UK384S; the defoamer is selected from at least one of UK272S and BYK-A530; the thixotropic agent is selected from polyamide wax; and the flake filler is selected from at least one of glass flakes, basalt flakes, and mica powder.

6. The protective coating according to claim 1, characterized in that, For component B, the amino resin is selected from CYMEL1130, and the catalyst is selected from DMP-30.

7. The protective coating according to claim 2, characterized in that, For component A, the molecular weight of the polysulfide rubber is 2500~3000, the conductive mica powder is selected from BC-C, the rheology modifier is selected from at least one of BYK-405, BYK-410, and BYK-411, and the fumed silica is M-5.

8. The protective coating according to claim 7, characterized in that, The polysulfide rubber is Thiokol® LP-32, a polysulfide rubber with a molecular weight of 2500.

9. The protective coating according to claim 1, characterized in that, The ratio of component A to component B is 10-15:1, and the amount of component B is 0.3-0.8% of that of component A.

10. The method for preparing the protective coating according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Preparation of component A of the primer layer: Add phosphorylated-sulfur heterocyclic modified epoxy resin, dispersant, leveling agent, defoamer, n-butanol and xylene to the mixture and disperse at 800~1500 r / min for 10~15 min; Continue to add zinc phosphate, flake filler, titanium dioxide, talc, and barite powder, and disperse at 800~1500 r / min until the fineness is ≤100μm; Next, add the thixotropic agent, heat to 50~65℃, and disperse at 800~1500r / min for 10~20min; Component A was obtained through filtration and packaging. S2. Preparation of component B of the primer layer: Add amino resin and catalyst, disperse at 800~1500 r / min for 10~30 min, filter and package to obtain component B; S3. Preparation of component A of the sealing layer: Add polysulfide rubber, conductive mica powder, rheology modifier, and fumed silica to the mixture, disperse at 800~1500 r / min for 20~30 min, filter and package to obtain component A; Before use, mix components A and B to obtain a primer layer, and mix components A and B to obtain a sealing layer. During application, first apply the primer layer to the sample, and then apply the sealing layer.

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