Flame-retardant anti-explosion multi-coating structure for oil and gas pipeline and preparation method

Abstract

The invention discloses a flame-retardant anti-explosion multi-coating structure for an oil and gas pipeline and a preparation method of the flame-retardant anti-explosion multi-coating structure, and belongs to the technical field of oil and gas pipeline safety protection. The inner wall of the oil and gas pipeline is coated with the functional layer 1, and the outer wall of the oil and gas pipeline is sequentially coated with the bonding layer, the functional layer 2 and the functional layer 3. Wherein the functional layer 1 is a polyurea rigid anticorrosive layer, the functional layer 2 is a polyurea flame-retardant layer, and the functional layer 3 is a polyurea explosion-proof layer; the polyurea flame-retardant layer is prepared from the following raw materials: polyether polyol, isocyanate, modified amino-terminated polyphosphate, a flame-retardant chain extender, an amine chain extender and a synergistic flame retardant. The process is simple, and the obtained oil and gas pipeline multi-coating structure has excellent conductivity and mechanical properties, excellent wear resistance, medium resistance, flame retardance, anti-explosion performance and the like, and meets the fireproof, anti-explosion and anti-corrosion requirements of related technical regulations of oil and gas pipelines on pipelines for oil and gas transmission.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas pipeline safety protection, and in particular to a flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines and a preparation method thereof. Background Art

[0002] The current service environment of oil and gas pipelines is harsh and complex, and the transported media are mostly flammable, explosive, or toxic. As the operating time increases, pipeline leakage and combustion and explosion accidents caused by factors such as pipeline material aging, manufacturing defects, third-party damage, natural disasters, and misoperation occasionally occur. Such accidents not only damage the ecological environment, cause casualties, and pose a huge safety hazard, but also cause huge economic losses.

[0003] Prior art discloses a composite crack arrest ring structure for oil and gas pipelines (publication number CN115449881A), comprising a first interface transition layer, a crack propagation prevention layer, a local reinforcement layer, a second interface transition layer, and a wear-resistant outer protective layer. These first interface transition layer, crack propagation prevention layer, local reinforcement layer, second interface transition layer, and wear-resistant outer protective layer are sequentially arranged on the outer surface of the metal pipeline from the inside out. While this patent discloses an anti-cracking structure for oil and gas pipelines to enhance their service life, it does not address the pipeline's corrosion resistance, flame retardancy, or explosion resistance, and its safety protection effectiveness remains unknown.

[0004] A prior art patent discloses a novel oil and gas pipeline (Announcement No. CN205806713U) comprising: an electrothermoplastic resin sealing layer, an inert metal film wrapped sealing layer, and a lightning protection layer, stacked in sequence from the inside out. A composite resin layer is interposed between the inert metal film wrapped sealing layer and the lightning protection layer to withstand the internal pressure of the pipeline during operation. This patent discloses a novel oil and gas pipeline with excellent antistatic and corrosion properties and a 30-year service life, but again, it does not address safety features such as flame retardancy and explosion resistance.

[0005] Based on the above defects, it is necessary to provide a flame retardant and explosion-proof multi-coating structure and preparation method for oil and gas pipelines to provide a new long-term and effective protection means to increase and enhance the anti-corrosion, flame retardant, explosion-proof and other safety protection functions of oil and gas pipelines. Summary of the Invention

[0006] The purpose of the present invention is to provide a flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines with good anti-corrosion performance, flame retardant performance, explosion-proof performance, antistatic performance and aging resistance.

[0007] To achieve the above objectives, the present invention first provides a flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines, comprising a functional layer 1 coated on the inner wall of the oil and gas pipeline, and an adhesive layer, a functional layer 2, and a functional layer 3 sequentially coated on the outer wall of the oil and gas pipeline; wherein the functional layer 1 is a polyurea rigid anti-corrosion layer, the functional layer 2 is a polyurea flame-retardant layer, and the functional layer 3 is a polyurea explosion-proof layer;

[0008] The raw materials of the polyurea flame retardant layer include polyether polyol, isocyanate, modified amino-terminated polyphosphate, flame retardant chain extender, amine chain extender, and synergistic flame retardant;

[0009] Wherein, the structural formula of the flame retardant chain extender is as follows:

[0010]

[0011] The structural formula of the modified amino-terminated polyphosphate is as follows:

[0012]

[0013] Wherein, n is a positive integer, preferably a positive integer of 1-100, and more preferably a positive integer of 10-50.

[0014] Furthermore, the raw materials of the polyurea rigid anti-corrosion layer include isocyanate, polyether polyol, amine chain extender, and inorganic filler; the raw materials of the polyurea explosion-proof layer include polyether polyol and / or polyester polyol, isocyanate, amino-terminated polyether, amine chain extender, and functionalized multi-component nano-composite material; the bonding layer is a polyurea matching primer, and the oil and gas pipeline is made of carbon steel.

[0015] Furthermore, the polyether polyol includes one or more of polyoxypropylene ether polyol (PPG210 / PPG220), polytetramethylene glycol (PTMG650 / PTMG1000), castor oil polyol and aliphatic amino-terminated polyether (PC473 / TAE280); the polyester polyol is polyε-caprolactone polyol (PCL210), the amino-terminated polyether includes D2000, One or more of T5000 and polytetramethylenetetramethylenediamine P1000.

[0016] Further, the isocyanate includes one or more of polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate (MDI-100 and MDI-50) and carbodiimide-modified diphenylmethane diisocyanate;

[0017] The amine chain extender includes one or more of 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,5-diethyltoluenediamine, dimethylthiotoluenediamine, N,N'-dialkylmethyldiamine and N,N'-dialkylphenylenediamine;

[0018] The inorganic filler is one or more of silicon micropowder, feldspar powder and barium sulfate;

[0019] The flame retardant system consists of a flame retardant amine chain extender, a modified terminal amino polyphosphate and a synergistic flame retardant. The synergistic flame retardant is one or more of aluminum hydroxide, aluminum hypophosphite and expandable graphite (80 mesh, 100 mesh, 150 mesh).

[0020] The functionalized multi-component nanocomposite material is at least two of functionalized carbon nanotubes, graphene oxide, layered SnO2 / ZnO nanostructures, and nano-γ-Fe2O3 particles.

[0021] Furthermore, the raw materials of the polyurea rigid anti-corrosion layer, the polyurea flame retardant layer and the polyurea explosion-proof layer also include one or more of a diluent, a water scavenger, a catalyst, an antistatic agent and a color paste.

[0022] Furthermore, the diluent is one of 2,2,4-trimethyl 1,3-pentanediol diisobutyrate and propylene glycol cyclic carbonate;

[0023] The dehydrating agent is 3A molecular sieve; the catalyst is an organic bismuth catalyst; and the color paste is a common commercially available color paste.

[0024] The polyurea rigid anti-corrosion layer of the functional layer 1 is polymerized by component A and component B. The raw materials used in component A include, by weight: 20-50 parts of polyether polyol, 50-80 parts of isocyanate, and 4-10 parts of diluent; the raw materials used in component B include, by weight: 25-80 parts of polyether polyol, 5-35 parts of amine chain extender, 10-20 parts of inorganic filler, 4-5 parts of diluent, 4-5 parts of dehydrating agent, 0.5-5 parts of catalyst, and 1-5 parts of color paste.

[0025] The polyurea flame retardant layer of the functional layer 2 is polymerized by two systems, component C and component D. The raw materials used in component C include, by weight: 30-60 parts of polyether polyol and 30-60 parts of diisocyanate; the raw materials used in component D include, by weight: 30-50 parts of polyether polyol, 5-20 parts of modified terminal amino polyphosphate, 1-10 parts of flame retardant chain extender, 5-35 parts of amine chain extender, 1-10 parts of synergistic flame retardant, 4-5 parts of water scavenger, 0.5-5 parts of catalyst and 1-5 parts of color paste.

[0026] The polyurea explosion-proof layer of the functional layer 3 is polymerized by two systems, component E and component F. The raw materials used in component E include, by weight, 10 to 30 parts of polyether polyol, 10 to 30 parts of polyester polyol, 50 to 80 parts of isocyanate, and 4 to 10 parts of diluent; the raw materials used in component F include, by weight, 10 to 35 parts of amino-terminated polyether, 10 to 30 parts of polyether polyol, 20 to 50 parts of amine chain extender, 0.5 to 3 parts of functionalized multi-component nanocomposite material, 4 to 10 parts of antistatic agent, 4 to 5 parts of diluent, 4 to 5 parts of dehydrating agent, 0.5 to 5 parts of catalyst, and 1 to 5 parts of color paste.

[0027] Furthermore, the flame retardant amine chain extender (FR-1) is prepared by the following steps:

[0028] S1. Preparation of crude product A

[0029] Phosphorus oxychloride and sorbitol are dissolved in a tetrahydrofuran / triethylamine solution, and reacted for a predetermined time after heating under the catalysis of anhydrous aluminum trioxide. The crude product A is obtained by distillation under reduced pressure, washing, and filtering.

[0030] S2. Preparation of flame retardant chain extender

[0031] The obtained crude product A is reacted with excess acetaminophen under the action of potassium carbonate / butanone solution, and the phenolic hydroxyl group replaces Cl to obtain product B. The product B is reacted in a sodium hydroxide solution, washed and dried by reduced pressure distillation to obtain the flame retardant amine chain extender.

[0032] The preparation process is as follows:

[0033]

[0034] Furthermore, the modified amino-terminated polyphosphate (FR-2) is prepared by the following steps:

[0035] S1. Preparation of crude product C

[0036] At a reaction temperature of 20±5°C, diethylene glycol was added dropwise to phenylphosphoryl dichloride to remove HCl to obtain crude product C;

[0037] S2. Preparation of modified amino-terminated polyphosphate

[0038] The crude product C and ammonia are used as raw materials, a four-way catalyst Ni-Cu-Cr-La is added, and a gas-liquid-solid three-phase reaction is carried out in a hydrogen atmosphere. First, the hydroxyl group of the intermediate product is dehydrogenated to form a carbonyl group under the action of the catalyst, and then ammonia is introduced to aminate and dehydrate the carbonyl group to form eneimine. Finally, hydrogen is introduced to hydrogenate and reduce the eneimine to an amino-terminated polyphosphate.

[0039] The preparation process is as follows:

[0040]

[0041] Specifically, 7 mol of phenylphosphoryl dichloride is added to the synthesis apparatus, the temperature maintained at 10-20°C. Subsequently, 8 mol of dodecacycloalkanediol is added dropwise to the phenylphosphoryl dichloride. As the esterification reaction proceeds, the temperature gradually increases, and a total of 14 mol of by-product hydrogen chloride is removed during the reaction to obtain an intermediate product. The intermediate product and ammonia are then used as raw materials in a gas-liquid-solid three-phase reaction over a four-way catalyst Ni-Cu-Cr-La, a hydrogen atmosphere, a reaction pressure of 0.03-0.15 MPa, and a reaction temperature of 50-80°C for 2-5 hours. First, the hydroxyl groups in the intermediate product are dehydrogenated to form carbonyl groups under the action of the catalyst. Ammonia is then introduced to aminate and dehydrate the carbonyl groups to form eneimine. Finally, hydrogen is introduced to hydrogenate the eneimine to form the modified amino-terminated polyphosphate FR-2.

[0042] The present invention also provides a method for preparing the flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines as described in any one of the above, comprising:

[0043] sandblasting or polishing the oil and gas pipeline;

[0044] Mixing the raw materials of the functional layer 1 and spraying them on the inner wall of the oil and gas pipeline to prepare a polyurea rigid anti-corrosion layer;

[0045] Applying the polyurea supporting primer by brushing, rolling or spraying on the outside of the oil and gas pipeline to prepare a bonding layer;

[0046] The raw materials of the functional layer 2 are mixed and sprayed on the outside of the bonding layer to prepare a polyurea flame retardant layer. The spraying interval is 4-48 hours after the primer is cured;

[0047] The raw materials of the functional layer 3 are mixed and sprayed on the outer side of the functional layer 2 to prepare a polyurea explosion-proof layer. The spraying interval is within 24 hours after the functional layer 2 is cured.

[0048] The present invention also provides a polyurea flame-retardant coating, characterized in that it comprises 30 to 60 parts of polyether polyol and 30 to 60 parts of diisocyanate in parts by weight; the raw materials used for component D comprise, in parts by weight: 30 to 50 parts of polyether polyol, 5 to 20 parts of modified amino-terminated polyphosphate, 1 to 10 parts of flame retardant chain extender, 5 to 35 parts of amine chain extender, and 1 to 10 parts of synergistic flame retardant; the structural formulas of the modified amino-terminated polyphosphate and the flame retardant chain extender are as shown in FR-1 and FR-2 above.

[0049] The present invention has the following beneficial effects compared to the prior art:

[0050] (1) The flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines of the present invention, wherein the polyurea rigid anti-corrosion layer is formulated based on the group contribution analysis method, giving the polyurea high density, high cross-linking and high rigidity, preparing a continuous and dense rigid polyurea, which can improve the polyurea's anti-corrosion and anti-seepage performance; the polyphenyl in polymethylene polyphenyl isocyanate can improve the polyurea's rigidity, cross-linking degree and thermal aging performance.

[0051] The polyurea flame retardant layer has both excellent mechanical properties and flame retardant properties through the synergistic effect of flame retardants; the phosphorus and nitrogen elements in the modified terminal amino polyphosphate can provide high flame retardancy, and the phenyl group can improve the thermal aging performance; the trifunctional amine chain extender can react with polyurea to be connected to the molecular chain without negatively affecting the mechanical properties and system compatibility; synergistic flame retardants such as aluminum hydroxide, aluminum hypophosphite and graphite are all powder flame retardants that can suppress smoke and resist dripping; the synergistic effect of the flame retardant system not only gives polyurea excellent flame retardant properties, but also does not have a negative impact on the mechanical properties. It can be used in oil and gas pipelines to achieve environmentally friendly, efficient flame retardant and safety protection effects.

[0052] The polyurea explosion-proof layer is designed with a high-performance polyurea matrix resin formula based on the group contribution analysis method, giving the polyurea excellent mechanical properties such as high strength and high elongation; the anti-explosion performance of the polyurea is greatly improved by adding functionalized multi-component nanocomposites.

[0053] (2) The flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines of the present invention can increase and enhance the anti-corrosion, flame-retardant, explosion-proof and other safety protection functions of oil and gas pipelines. The process of the present invention is simple, and the resulting multi-coating structure for oil and gas pipelines has excellent electrical conductivity and mechanical properties, excellent wear resistance, medium resistance, flame retardancy and explosion-proof properties, etc., and meets the fire, explosion and corrosion protection requirements for oil and gas pipelines in the "Related Technical Regulations for Oil and Gas Pipelines". BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a structural schematic diagram of an oil and gas pipeline according to the present invention;

[0055] Figure 2 This is a schematic structural diagram of a flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines according to the present invention;

[0056] Figure 3 This is a schematic diagram of the structural decomposition of a flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines according to the present invention;

[0057] Figure 4 This is a vertical combustion diagram of the functional layer 2 in the multi-coating structure in Example 2 of the present invention;

[0058] Figure 5 It is a vertical combustion diagram of Comparative Example 1 of the present invention;

[0059] Figure 6This is a thermogravimetric test diagram of the functional layer 2 in the multi-coating structure of Example 2 of the present invention and the comparative example 1. DETAILED DESCRIPTION

[0060] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0061] Example 1

[0062] like Figure 1-3 As shown, a functional layer 1 in a flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines, namely a polyurea rigid anti-corrosion layer, includes: component A and component B, wherein component A includes the following raw materials: polyether polyol, isocyanate and diluent; component B includes the following raw materials: polyether polyol, amine chain extender, inorganic filler, diluent, dehydrating agent, catalyst and color paste.

[0063] In this embodiment, the polyether polyol in component A uses 22 parts by weight of castor oil polyol AC320, the isocyanate uses 35 parts by weight of polymethylene polyphenyl isocyanate and 39 parts by weight of diphenylmethane diisocyanate, and the diluent uses 4 parts by weight of propylene glycol cyclic carbonate; the polyether polyol in component B uses 38 parts by weight of castor oil polyol AC320 and 27 parts by weight of polyether alcohol TAE285, the amine chain extender uses 5 parts by weight of 3,5-diethyltoluenediamine, the inorganic filler uses 15 parts by weight of silicon powder, the dehydrator uses 5 parts by weight of 3A molecular sieve, the diluent uses 5 parts by weight of 2.2.4-trimethyl 1,3-pentanediol diisobutyrate, the color paste uses 4.5 parts by weight of commercially available color pastes of various colors, and the catalyst uses 0.5 parts by weight of organic bismuth catalyst C1.

[0064] A functional layer 2, i.e., a polyurea flame retardant layer, in a flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines comprises: a C component and a D component, wherein the C component comprises the following raw materials: polyether polyol and diisocyanate; and the D component comprises the following raw materials: polyether polyol, an amine chain extender, a flame retardant, a water scavenger, a catalyst, and a color paste.

[0065] In this embodiment, the polyether polyol in component C is 52 parts by weight of polyoxypropylene ether diol PPG220, and the diisocyanate is 48 parts by weight of diphenylmethane diisocyanate; the polyether polyol in component D is 38 parts by weight of polyoxypropylene ether diol PPG220, the amine chain extender is 19 parts by weight of 3,5-diethyltoluenediamine and 9 parts by weight of N,N'-dialkylmethyldiamine, the flame retardant is 13 parts by weight of modified terminal amino polyphosphate FR-2 (structural formula shown below), 6 parts of flame retardant amine chain extender FR-1 (structural formula shown below) and 6 parts of aluminum hypophosphite, the dehydrator is 5 parts by weight of 3A molecular sieve, the color paste is 3.5 parts by weight of commercially available color pastes of various colors; the catalyst is 0.5 parts by weight of organic bismuth catalyst C1.

[0066]

[0067] The preparation method for FR-2 involves adding 7 mol of phenylphosphoryl dichloride to a synthesis apparatus, maintaining the temperature at 10-20°C. 8 mol of dodecacycloalkanediol is then added dropwise to the phenylphosphoryl dichloride. As the esterification reaction proceeds, the temperature gradually increases, and a total of 14 mol of by-product hydrogen chloride is removed during the reaction, yielding an intermediate product. The intermediate product and ammonia are then reacted in a gas-liquid-solid three-phase reaction over a Ni-Cu-Cr-La quaternary catalyst, a hydrogen atmosphere, a reaction pressure of 0.03-0.15 MPa, and a temperature of 70°C for 3 hours. First, the hydroxyl groups in the intermediate product are dehydrogenated to form carbonyl groups under the action of the catalyst. Ammonia is then introduced to ammoniate and dehydrate the carbonyl groups to form eneimine. Finally, hydrogen is introduced to hydrogenate the eneimine to form the modified amino-terminated polyphosphate FR-2.

[0068] Functional layer 3, i.e., a polyurea explosion-proof layer, in a flame-retardant and explosion-proof multi-coating structure for oil and gas pipelines comprises: an E component and an F component, wherein the E component comprises the following raw materials: a polyether / polyester polyol, a diisocyanate, and a diluent; and the F component comprises the following raw materials: an amino-terminated polyether, a polyether polyol, an amine chain extender, a functionalized multi-component nanocomposite material, an antistatic agent, a water scavenger, a catalyst, and a color paste.

[0069] In this embodiment, the polyether polyol in component E is 14 parts by weight of polytetramethylene ether glycol PTMG1000 and 13 parts by weight of ε-caprolactone polyol PCL210, the isocyanate is 63 parts by weight of diphenylmethane diisocyanate, and the diluent is 10 parts by weight of propylene glycol cyclic carbonate; the terminal amino polyether in component F is 25 parts by weight of D2000, the polyether polyol adopts 20 parts by weight of polytetramethylene glycol PTMG1000, the amine chain extender adopts 20 parts by weight of 3,5-diethyltoluenediamine and 20 parts by weight of 3,3'-dichloro-4,4'-diaminodiphenylmethane, the functionalized multi-component nanocomposite material adopts 1 part by weight of functionalized carbon nanotubes and 1 part by weight of layered SnO2 / ZnO nanostructure, the antistatic agent adopts 5 parts by weight of antistatic agent, the dehydrator adopts 5 parts by weight of 3A molecular sieve, the color paste adopts 2.5 parts by weight of commercially available color pastes of various colors; and the catalyst adopts 0.5 parts by weight of C1.

[0070] This embodiment also provides a method for preparing a flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines, including:

[0071] S1. Sandblasting or grinding the metal layer;

[0072] S2, mixing component A and component B in a volume ratio of 1:1 and spraying them on the inner layer of the polished metal layer to prepare functional layer 1;

[0073] S3. Brush / roll / spray a polyurea primer specifically for the carbon steel substrate onto the outside of the metal layer to prepare a bonding layer;

[0074] S4. Mix component C and component D in a volume ratio of 1:1 and spray them on the outside of the bonding layer to prepare functional layer 2. The spraying interval is 4-48 hours after the bonding layer is cured;

[0075] S5. Mix component E and component F in a volume ratio of 1:1 and spray them on the outside of the functional layer 2 to prepare the functional layer 3. The spraying interval is within 24 hours after the functional layer 2 is cured.

[0076] Example 2

[0077] A functional layer 1, i.e., a polyurea rigid anti-corrosion layer, in a flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines comprises: component A and component B, wherein component A comprises the following raw materials: polyether polyol, polyisocyanate, and diluent; and component B comprises the following raw materials: polyether polyol, amine chain extender, inorganic filler, diluent, dehydrating agent, catalyst, and color paste.

[0078] In this embodiment, the polyether polyol in component A is 25 parts by weight of polyoxypropylene ether glycol PPG210, the isocyanate in component A is 38 parts by weight of polymethylene polyphenyl isocyanate and 32 parts by weight of diphenylmethane diisocyanate, the diluent in component A is 5 parts by weight of 2.2.4-trimethyl 1.3-pentanediol diisobutyrate; the polyether polyol in component B is 23 parts by weight of castor oil polyol AC320 and 12 parts by weight of propylene glycol polyol. The ingredients are polyoxypropylene ether glycol PPG210 and 30 parts by weight of polyether alcohol TAE285, 8 parts by weight of 3,5-diethyltoluenediamine as chain extender, 12 parts by weight of feldspar powder as inorganic filler, 5 parts by weight of 3A molecular sieve as dehydrating agent, 5 parts by weight of 2,2.4-trimethyl 1,3-pentanediol diisobutyrate as diluent, 4.5 parts by weight of commercially available color pastes of various colors, and 0.5 parts by weight of C1 as catalyst.

[0079] A functional layer 2, i.e., a polyurea flame retardant layer, in a flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines comprises: a C component and a D component, wherein the C component comprises the following raw materials: polyether polyol and diisocyanate; and the D component comprises the following raw materials: polyether polyol, an amine chain extender, a flame retardant, a water scavenger, a catalyst, and a color paste.

[0080] In this embodiment, the polyether polyol in component C uses 50 parts by weight of polyoxypropylene ether glycol PPG220, and the isocyanate in component C uses 50 parts by weight of carbodiimide-modified diphenylmethane diisocyanate; the polyether polyol in component D uses 39 parts by weight of polyoxypropylene ether glycol PPG220, the chain extender uses 18 parts by weight of 3,5-diethyltoluenediamine and 10 parts by weight of N,N'-dialkylmethyldiamine, the flame retardant uses 15 parts by weight of modified terminal amino polyphosphate FR-2 (same as in Example 1), 6 parts of flame retardant amine chain extender FR-1 and 5 parts of 80 mesh expandable graphite, the dehydrator uses 4 parts by weight of 3A molecular sieve, the color paste uses 2.5 parts by weight of commercially available color pastes of various colors; and the catalyst uses 0.5 parts by weight of C1.

[0081] Functional layer 3, i.e., a polyurea explosion-proof layer, in a flame-retardant and explosion-proof multi-coating structure for oil and gas pipelines comprises: an E component and an F component, wherein the E component comprises the following raw materials: a polyether / polyester polyol, a diisocyanate, and a diluent; and the F component comprises the following raw materials: an amino-terminated polyether, a polyether polyol, an amine chain extender, a functionalized multi-component nanocomposite material, an antistatic agent, a diluent, a water scavenger, a catalyst, and a color paste.

[0082] In this embodiment, the polyether polyol in component E uses 38 parts by weight of polytetramethylene glycol PTMG1000, and the isocyanate in component E uses 62 parts by weight of diphenylmethane diisocyanate; the polyether polyol in component F uses 39 parts by weight of polytetramethylene glycol PTMG1000, the chain extender uses 23 parts by weight of 3,5-diethyltoluenediamine, 12 parts by weight of N,N'-dialkylmethyldiamine and 7 parts by weight of 3,3'-dichloro-4,4'-diaminodiphenylmethane, the functionalized multi-nanocomposite material uses 1.5 parts by weight of functionalized carbon nanotubes and 0.5 parts by weight of functionalized graphene, the antistatic agent uses 8 parts by weight of antistatic agent, the dehydrator uses 5 parts by weight of 3A molecular sieve, the color paste uses 3.5 parts by weight of commercially available color pastes of various colors; and the catalyst uses 0.5 parts by weight of C1.

[0083] This embodiment also provides a method for preparing a flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines, including:

[0084] S1. Sandblasting or grinding the metal layer;

[0085] S2, mixing component A and component B in a volume ratio of 1:1 and spraying them on the inner layer of the polished metal layer to prepare functional layer 1;

[0086] S3. Brush / roll / spray a polyurea primer specifically for the carbon steel substrate onto the outside of the metal layer to prepare a bonding layer;

[0087] S4. Mix component C and component D in a volume ratio of 1:1 and spray them on the outside of the bonding layer to prepare functional layer 2. The spraying interval is 4-48 hours after the bonding layer is cured;

[0088] S5. Mix component E and component F in a volume ratio of 1:1 and spray them on the outside of the functional layer 2 to prepare the functional layer 3. The spraying interval is within 24 hours after the functional layer 2 is cured.

[0089] Example 3

[0090] A functional layer 1, i.e., a polyurea rigid anti-corrosion layer, in a flame-retardant and explosion-resistant multi-coating structure for oil and gas pipelines comprises: component A and component B, wherein component A comprises the following raw materials: polyether polyol, polyisocyanate, and diluent; and component B comprises the following raw materials: polyether polyol, amine chain extender, inorganic filler, diluent, dehydrating agent, catalyst, and color paste.

[0091] In this embodiment, the polyether polyol in component A is 21 parts by weight of castor oil polyol AC320, the isocyanate in component A is 38 parts by weight of polymethylene polyphenyl isocyanate and 36 parts by weight of carbodiimide-modified diphenylmethane diisocyanate, the diluent in component A is 5 parts by weight of propylene glycol cyclic carbonate; the polyether polyol in component B is 35 parts by weight of polyoxypropylene ether glycol PPG210 and 30 parts by weight of propylene glycol cyclic carbonate. The invention discloses a novel polyether alcohol TAE285, a chain extender comprising 6 parts by weight of 3,5-diethyltoluenediamine and 5 parts by weight of 3,3'-dichloro-4,4'-diaminodiphenylmethane, an inorganic filler comprising 11 parts by weight of barium sulfate, a water scavenger comprising 5 parts by weight of 3A molecular sieve, a diluent comprising 5 parts by weight of propylene glycol cyclic carbonate, a color paste comprising 2.5 parts by weight of commercially available color pastes, and a catalyst comprising 0.5 parts by weight of C1.

[0092] A functional layer 2, i.e., a polyurea flame retardant layer, in a flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines comprises: a C component and a D component, wherein the C component comprises the following raw materials: polyether polyol and diisocyanate; and the D component comprises the following raw materials: polyether polyol, an amine chain extender, a flame retardant, a water scavenger, a catalyst, and a color paste.

[0093] In this embodiment, the polyether polyol in component C uses 54 parts by weight of polyoxypropylene ether diol PPG220, and the isocyanate in component C uses 46 parts by weight of diphenylmethane diisocyanate; the polyether polyol in component D uses 38 parts by weight of polyoxypropylene ether diol PPG220, the chain extender uses 20 parts by weight of 3,5-diethyltoluenediamine and 10 parts by weight of N,N'-dialkylmethyldiamine, the flame retardant uses 14 parts by weight of modified terminal amino polyphosphate FR-2 (same as in Example 1), 6 parts of flame retardant amine chain extender FR-1 and 5 parts of aluminum hypophosphite, the dehydrator uses 4 parts by weight of 3A molecular sieve, the color paste uses 2.4 parts by weight of commercially available color pastes of various colors; and the catalyst uses 0.6 parts by weight of C1.

[0094] Functional layer 3, i.e., a polyurea explosion-proof layer, in a flame-retardant and explosion-proof multi-coating structure for oil and gas pipelines comprises: an E component and an F component, wherein the E component comprises the following raw materials: a polyether / polyester polyol, a diisocyanate, and a diluent; and the F component comprises the following raw materials: an amino-terminated polyether, a polyether polyol, an amine chain extender, a functionalized multi-component nanocomposite material, an antistatic agent, a diluent, a water scavenger, a catalyst, and a color paste.

[0095] In this embodiment, the polyether polyol in component E is 20 parts by weight of polytetramethylene ether glycol PTMG1000 and 6 parts by weight of polytetramethylene ether glycol PTMG650, the isocyanate in component E is 64 parts by weight of diphenylmethane diisocyanate, the diluent in component E is 10 parts by weight of propylene glycol cyclic carbonate; the amino-terminated polyether in component F is 24 parts by weight of D2000, the polyether polyol adopts 13 parts by weight of polytetramethylene glycol PTMG650, the chain extender adopts 20 parts by weight of 3,5-diethyltoluenediamine and 20 parts by weight of N,N'-dialkylmethyldiamine, the functionalized multi-component nanocomposite material adopts 2.5 parts by weight of functionalized carbon nanotubes and 0.5 parts by weight of functionalized graphene, the antistatic agent adopts 10 parts by weight of antistatic agent, the water scavenger adopts 5 parts by weight of 3A molecular sieve, the color paste adopts 4.5 parts by weight of commercially available color pastes of various colors; and the catalyst adopts 0.5 parts by weight of C1.

[0096] This embodiment also provides a method for preparing a flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines, including:

[0097] S1. Sandblasting or grinding the metal layer;

[0098] S2, mixing component A and component B in a volume ratio of 1:1 and spraying them on the inner layer of the polished metal layer to prepare functional layer 1;

[0099] S3. Brush / roll / spray a polyurea primer specifically for the carbon steel substrate onto the outside of the metal layer to prepare a bonding layer;

[0100] S4. Mix component C and component D in a volume ratio of 1:1 and spray them on the outside of the bonding layer to prepare functional layer 2. The spraying interval is 4-48 hours after the bonding layer is cured;

[0101] S5. Mix component E and component F in a volume ratio of 1:1 and spray them on the outside of the functional layer 2 to prepare the functional layer 3. The spraying interval is within 24 hours after the functional layer 2 is cured.

[0102] Comparative Example 1

[0103] A common polyurea protective material comprises: component A and component B, wherein component A comprises the following raw materials: polyether polyol and isocyanate; component B comprises the following raw materials: polyether polyol, amine chain extender, water scavenger, catalyst and color paste.

[0104] In Comparative Example 1, the polyether polyol in component A uses 52 parts by weight of polyoxypropylene ether diol PPG220, and the isocyanate in component A uses 48 parts by weight of diphenylmethane diisocyanate; the polyether polyol in component B uses 65 parts by weight of polyoxypropylene ether diol PPG220, the chain extender uses 18 parts by weight of 3,5-diethyltoluenediamine and 9 parts by weight of N,N'-dialkylmethyldiamine, the dehydrator uses 5 parts by weight of 3A molecular sieve, the color paste uses 2.5 parts by weight of commercially available color pastes of various colors, and the catalyst uses 0.5 parts by weight of C1.

[0105] like Figure 4 and 5 As shown, it can be seen that the functional layer 2 of Example 2 extinguishes faster (with reference to UL 94 test standard, the test was conducted using a polyurea sample of the sprayed functional layer 2).

[0106] The performance of the functional layer 1, the functional layer 2 and the functional layer 3 prepared in the above Examples 1 to 3 were tested respectively, and the performance of the above Comparative Example 1 was also tested. The experimental results are shown in Table 1.

[0107] The tensile strength and elongation at break were tested in accordance with GB / T 528-2009 "Rubber, vulcanized or thermoplastic rubber - Determination of tensile stress-strain properties", the tear strength was tested in accordance with GB / T 529-2008 "Rubber, vulcanized or thermoplastic rubber - Determination of tear strength (trouser-shaped, rectangular and crescent-shaped test specimens)", the hardness was tested in accordance with GB / T 531.1-2008 "Rubber, vulcanized or thermoplastic rubber - Determination of indentation hardness - Part 1: Shore durometer method (Shore hardness)", the bonding strength was tested in accordance with GB / T 5210-2006 "Paints and varnishes - Pull-off adhesion test", the liquid resistance was tested in accordance with GB / T 9274-1988 "Paints and varnishes - Determination of resistance to liquid media", and the oxygen index was tested in accordance with GB / T The vertical burning grade is tested with reference to UL94-2021 "Fire test for plastic materials for equipment and electrical components". The impact resistance is tested with reference to GBT 20624.2-2006 "Paints and varnishes - Rapid deformation (impact resistance) test Part 2: Drop weight test (small area punch)". The resistivity is tested with reference to GB / T31838.2-2019 "Dielectric and resistive properties of solid insulating materials - Part 2: Resistance characteristics (DC method) Volume resistance and volume resistivity".

[0108] Table 1 Performance test results of different functional layers prepared in different embodiments

[0109]

[0110]

[0111] As can be seen from Table 1, the elongation of functional layer 1 is about 10%, and the hard segment is Shore D60-70. It is a typical rigid polyurea coating with the characteristics of high hardness, high strength, and high adhesion. It also has excellent medium resistance and can withstand liquid media for 90 days without rust, blistering, or shedding. Compared with the ordinary polyurea in comparative example 1, which can withstand liquid media for 30 days, the anti-corrosion effect is good.

[0112] The tensile strength of functional layer 2 is above 15 MPa, the elongation at break is about 300%, and the adhesion under the polyurea primer specially applied to carbon steel substrate can reach above 8 MPa. It has good tensile strength, elongation at break and high adhesion. At the same time, under the coordinated effect of the flame retardant system, it also has good flame retardant properties, with an oxygen index of above 28%, and vertical combustion can reach UL-94V0 level. In comparative example 1, the oxygen index of ordinary polyurea is only 22.3%, and the combustion of the specimen in the vertical combustion test does not reach UL-94V2 level. In comparison, functional layer 2 has excellent flame retardant properties. In summary, functional layer 2 can make the mechanical properties meet the polyurea Type 1 standard while having good flame retardant properties.

[0113] Functional layer 3 has extremely high tensile strength and tear strength, with tensile strength exceeding 35 MPa and tear strength exceeding 110 N / mm. It also has good elongation at break and impact resistance, with elongation exceeding 200 and impact resistance exceeding 2 kg·m. The good elongation at break, excellent mechanical strength and impact resistance together give the functional layer 3 excellent wrapping and explosion-proof performance when subjected to explosions. In addition, the resistivity of the functional layer 3 is between 5 and 6*10 8 In the range, compared with 2.62*10 12 It has excellent electrical conductivity and excellent antistatic properties.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flame retardant and explosion-proof multi-coating structure for oil and gas pipelines, characterized in that: It comprises a functional layer 1 coated on the inner wall of the oil and gas pipeline, and a bonding layer, a functional layer 2 and a functional layer 3 coated on the outer wall of the oil and gas pipeline in sequence; wherein the functional layer 1 is a polyurea rigid anti-corrosion layer, the functional layer 2 is a polyurea flame retardant layer, and the functional layer 3 is a polyurea explosion-proof layer; The raw materials of the polyurea flame retardant layer include polyether polyol, isocyanate, modified amino-terminated polyphosphate, flame retardant chain extender, amine chain extender and synergistic flame retardant; Wherein, the structural formula of the flame retardant chain extender is as follows: The structural formula of the modified amino-terminated polyphosphate is as follows: Wherein, n is a positive integer.

2. The flame retardant and explosion resistant multi-coating structure for oil and gas pipelines according to claim 1 is characterized in that: The raw materials of the polyurea rigid anti-corrosion layer include isocyanate, polyether polyol, amine chain extender, and inorganic filler; the raw materials of the polyurea explosion-proof layer include polyether polyol and / or polyester polyol, isocyanate, amino-terminated polyether, amine chain extender, and functionalized multi-nano composite material; the bonding layer is a polyurea matching primer, and the oil and gas pipeline is made of carbon steel.

3. The flame retardant and explosion resistant multi-coating structure for oil and gas pipelines according to claim 1, characterized in that: The polyether polyol includes one or more of polyoxypropylene ether polyol, polytetrahydrofuran polyol, castor oil polyol and aliphatic amino-terminated polyether; the polyester polyol is poly-ε-caprolactone polyol, the amino-terminated polyether includes D2000, One or more of T5000 and polytetramethyleneimine P1000.

4. The flame retardant and explosion-resistant multi-coating structure for oil and gas pipelines according to claim 2, characterized in that: The isocyanate includes one or more of polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate and carbodiimide-modified diphenylmethane diisocyanate; The amine chain extender includes one or more of 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,5-diethyltoluenediamine, dimethylthiotoluenediamine, N,N'-dialkylmethyldiamine and N,N'-dialkylphenylenediamine; The inorganic filler is one or more of silicon micropowder, feldspar powder and barium sulfate; The synergistic flame retardant is one or more of aluminum hydroxide, aluminum hypophosphite and expandable graphite; The functionalized multi-component nano-composite material is at least two of functionalized carbon nanotubes, graphene oxide, layered SnO2 / ZnO nanostructures, and nano-γ-Fe2O3 particles.

5. The flame retardant and explosion resistant multi-coating structure for oil and gas pipelines according to claim 1 or 2, characterized in that: The raw materials of the polyurea rigid anticorrosive layer, the polyurea flame retardant layer and the polyurea explosion-proof layer also include one or more of a diluent, a dehydrating agent, a catalyst, an antistatic agent and a color paste.

6. The flame retardant and explosion resistant multi-coating structure for oil and gas pipelines according to claim 5, characterized in that: The diluent is one of 2,2,4-trimethyl 1,3-pentanediol diisobutyrate and propylene glycol cyclic carbonate; The dehydrating agent is 3A molecular sieve; the catalyst is an organic bismuth catalyst.

7. The flame retardant and explosion resistant multi-coating structure for oil and gas pipelines according to claim 1, characterized in that: The flame retardant amine chain extender is prepared by the following steps: S1. Preparation of crude product A Phosphorus oxychloride and sorbitol are dissolved in tetrahydrofuran / triethylamine solution, and reacted for a preset time after heating under the catalysis of anhydrous aluminum oxide, and then subjected to reduced pressure distillation, washing, and filtering to obtain a crude product A; S2. Preparation of flame retardant chain extender The obtained crude product A is reacted with excess acetaminophen under the action of potassium carbonate / butanone solution, and the phenolic hydroxyl group replaces Cl to obtain product B. The product B is reacted in a sodium hydroxide solution, and is washed and dried by reduced pressure distillation to obtain the flame retardant amine chain extender.

8. The flame retardant and explosion resistant multi-coating structure for oil and gas pipelines according to claim 1, characterized in that: The modified amine-terminated polyphosphate is prepared by the following steps: S1. Preparation of crude product C At a reaction temperature of 20±5°C, diethylene glycol was added dropwise to phenylphosphoryl dichloride to remove HCl to obtain a crude product C; S2. Preparation of modified amino-terminated polyphosphate The crude product C and ammonia are used as raw materials, a quaternary catalyst Ni-Cu-Cr-La is added, and a gas-liquid-solid three-phase reaction is carried out in a hydrogen atmosphere. First, the hydroxyl group of the intermediate product is dehydrogenated to form a carbonyl group under the action of the catalyst, and then ammonia is introduced to aminate and dehydrate the carbonyl group to form ene imine, and finally hydrogen is introduced to hydrogenate and reduce the ene imine to terminal amino polyphosphate.

9. A method for preparing a flame retardant and explosion resistant multi-coating structure for oil and gas pipelines according to any one of claims 1 to 8, characterized in that: include: sandblasting or grinding the oil and gas pipeline; Mixing and spraying the raw materials of the functional layer 1 on the inner wall of the oil and gas pipeline to prepare a polyurea rigid anti-corrosion layer; Applying the polyurea matching primer by brushing, rolling or spraying on the outside of the oil and gas pipeline to prepare a bonding layer; The raw materials of the functional layer 2 are mixed and sprayed on the outside of the bonding layer to prepare a polyurea flame retardant layer, and the spraying interval is 4-48 hours after the primer is cured; The raw materials of the functional layer 3 are mixed and sprayed on the outer side of the functional layer 2 to prepare a polyurea explosion-proof layer, and the spraying interval is within 24 hours after the functional layer 2 is cured.

10. A polyurea flame retardant coating, characterized in that: The invention comprises 30 to 60 parts of polyether polyol and 30 to 60 parts of diisocyanate by weight; the raw materials used for component D comprise 30 to 50 parts of polyether polyol, 5 to 20 parts of modified terminal amino polyphosphate, 1 to 10 parts of flame retardant chain extender, 5 to 35 parts of amine chain extender and 1 to 10 parts of synergistic flame retardant by weight; the structural formula of the modified terminal amino polyphosphate and the flame retardant chain extender is the structural formula described in claim 1.

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