Low-thermal-conductivity high-toughness modified fluorosilicon resin coating material, and preparation method and application thereof

Abstract

The application belongs to the technical field of special polymer coating materials, and specifically discloses a low-thermal-conductivity high-toughness modified fluorosilicon resin coating material, a preparation method thereof and application thereof. The material comprises fluorosilicon resin prepolymer, nano rubber, aerogel powder, inorganic fiber, ceramic particles and silane coupling agent, and can be used to prepare a metal surface coating with high wear resistance, low thermal conductivity and high toughness, and is particularly suitable for being used as a surface coating material of a drill pipe for oil well drilling, and can meet the stability requirements of the drill pipe under extreme chemical and high-temperature conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of special polymer coating materials, and specifically discloses a low-thermal-conductivity high-toughness modified fluorosilicone resin coating material as well as a preparation method and application thereof. BACKGROUND

[0002] In high-temperature stratum (such as geothermal well, deep oil and gas reservoir) drilling operations, the high thermal conductivity of the drill pipe can cause the tools such as downhole motor, electronic instrument and sensor to overheat and fail, and can also accelerate the mechanical loss of the drill pipe. Therefore, the low-thermal-conductivity drill pipe technology is one of the key technologies for deep well drilling. At present, the main technologies mainly include: 1. reducing the thermal conductivity by adjusting the composition of steel (such as increasing the content of Ni and Cr, and reducing the Fe-C ratio). For example, the thermal conductivity of the austenitic stainless steel drill pipe (~15 W / m·K) is lower than that of the conventional alloy steel (~45 W / m·K), but the cost is high and the strength is low; the high-nickel alloy drill pipe is resistant to high temperature and has low thermal conductivity, but the price is expensive and is only used for special working conditions. The material cost of this technology increases greatly, and it is difficult to be applied on a large scale, and the mechanical properties (such as tensile strength and torsional properties) may be deteriorated. 2. A heat insulation layer (such as ceramic fiber, aerogel or porous metal) is arranged between the inner wall and the outer wall of the drill pipe. For example, the thermal conductivity of the drill pipe filled with ceramic fiber can be reduced to 1-5 W / m·K, but the structural strength is reduced; the vacuum insulation drill pipe is similar to the principle of the thermos bottle, but the manufacturing process is complex and is easy to break and fail. The heat insulation layer of this technology is easy to compress or leak in the high-pressure drilling fluid environment, and it is difficult to achieve effective heat insulation at the connecting parts (such as threaded area) of the drill pipe. 3. A layer of resin material is coated on the surface of the drill pipe by physical spraying or chemical heat setting forming, which greatly improves the chemical stability and wear resistance of the drill pipe. However, the thermal conductivity is high and cannot meet the heat insulation requirements of high-temperature components.

[0003] Therefore, it is of great significance to develop a heat insulation drill pipe that can be used under high temperature conditions, so as to improve the drilling efficiency, prolong the service life of the drill pipe and ensure the rapid and safe operation of the drilling site. SUMMARY

[0004] In view of the above problems existing in the prior art, the application provides a low-thermal-conductivity high-toughness modified fluorosilicone resin coating material, a preparation method and application thereof, which can be used to prepare a heat insulation drill pipe with high wear resistance, low thermal conductivity and high toughness for use under high temperature conditions.

[0005] In a first aspect, the application provides a low-thermal-conductivity high-toughness modified fluorosilicone resin coating material, which comprises fluorosilicone resin prepolymer, nano rubber, aerogel powder, inorganic fiber, ceramic particles and silane coupling agent.

[0006] The fluorosilicone resin prepolymer contains structural unit a as shown in formula (1), structural unit b as shown in formula (2) and structural unit c as shown in formula (3):

[0007]

[0008] Formula (1);

[0009] wherein m is an integer from 0 to 2, x, y, z are molar numbers, and x:y:z = 1-8:1-8:1-8, R1 is hydrogen, methyl or phenyl;

[0010] The content of the nano rubber is 5-20 parts by weight, the content of the aerogel powder is 0.1-2 parts by weight, the content of the inorganic fiber is 5-40 parts by weight, the content of the ceramic particles is 10-20 parts by weight, and the content of the silane coupling agent is 0.5-5 parts by weight, based on 100 parts of the total weight of the fluorosilicone resin prepolymer.

[0011] In some embodiments, x:y:z = 3-8:1-2:3-6.

[0012] In some embodiments, the preparation method of the fluorosilicone resin prepolymer comprises mixing monomer A having structural unit a, monomer B having structural unit b after hydrolysis, and monomer C having structural unit c in the presence of a solvent and a catalyst to cause a polymerization reaction. In some embodiments, monomer A is methyltrifluoropropylsiloxane or methyltrifluoromethylsiloxane. In some embodiments, monomer B is tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), or silicic acid. In some embodiments, monomer C is phenylsiloxane, methylphenylsiloxane, or diphenylsiloxane. In some embodiments, increasing the proportion of monomer A increases the flexibility of the coating, reduces the thermal conductivity, and reduces the mechanical strength; increasing the proportion of monomer B increases the crosslinking density and wear resistance, but increases the brittleness; increasing the proportion of monomer C increases the heat resistance, but reduces the processability, and therefore, the molar ratio of monomer A, monomer B, and monomer C needs to be controlled at 3-8:1-2:3-6 to balance the various properties. In some embodiments, the temperature of the polymerization reaction is 70-90°C, and the time is 2-4 hours. In some embodiments, the solvent is an alcohol solvent and water, the addition amount of the alcohol solvent is 60-150% of the total mass of the monomers, and the addition amount of the water is 1-3% of the total mass of the monomers. In some embodiments, the alcohol solvent is ethanol and / or isopropyl alcohol, which functions to adjust the viscosity, and the water can initiate hydrolysis. In some embodiments, the catalyst is an organic tin catalyst (such as dibutyltin dilaurate DBTL) or a phthalate catalyst (such as titanium tetrabutoxide TBT), which functions to accelerate the hydrolysis and condensation of the alkoxyl groups to increase the reaction rate, and the addition amount is usually 0.1-1 wt% of the total mass of the monomers.

[0013] In some embodiments, the nano rubber is any one of hydrogenated nitrile rubber, cis-butadiene rubber, chlorobutyl rubber, or isoprene rubber, or a mixture of two or more thereof. In some embodiments, the particle size of the nano rubber is 50-500 nm.

[0014] In some embodiments, the aerogel is any one or a mixture of two or more of silica aerogel, silicon carbide aerogel, aluminum oxide aerogel, or zirconium dioxide aerogel. In some embodiments, the aerogel powder has an average particle size of 10-100 μm.

[0015] In some embodiments, the inorganic fiber is any one or a mixture of two or more of chopped quartz fiber, basalt fiber, or glass fiber. In some embodiments, the inorganic fiber has a diameter of 5-10 μm.

[0016] In some embodiments, the ceramic particle is any one or a mixture of two or more of aluminum oxide ceramic particle or silicon carbide ceramic particle. In some embodiments, the ceramic particle has a particle size of 2-20 μm.

[0017] In some embodiments, the silane coupling agent is an amino silane coupling agent. In some embodiments, the amino silane coupling agent is any one of γ-aminopropyl triethoxysilane or γ-aminopropyl trimethoxysilane.

[0018] In a second aspect, the present application provides use of the low-thermal-conductivity high-toughness material as described above in a surface coating of a low-thermal-conductivity high-toughness article. In some embodiments, the low-thermal-conductivity high-toughness article is a drilling tool for oil well drilling. In some embodiments, the drilling tool for oil well drilling is a drill pipe.

[0019] In a third aspect, the present application provides a low-thermal-conductivity high-toughness article comprising a substrate and a coating formed on at least a portion of a surface of the substrate, the coating being made of the low-thermal-conductivity high-toughness modified fluorosilicon resin coating material as described above. In some embodiments, the low-thermal-conductivity high-toughness article is a drilling tool for oil well drilling. In some embodiments, the drilling tool for oil well drilling is a drill pipe. In some embodiments, the substrate is an alloy steel.

[0020] In a fourth aspect, the present application provides a method for preparing the low-thermal-conductivity high-toughness article as described above, comprising: providing a substrate; mixing a fluorosilicon resin prepolymer, a nano rubber, an aerogel powder, an inorganic fiber, a ceramic particle, and a silane coupling agent to form a slurry; applying the slurry to at least a portion of a surface of the substrate; and heating the slurry on the surface of the substrate to solidify the slurry, thereby obtaining the low-thermal-conductivity high-toughness article.

[0021] In some embodiments, the mixing is performed by mechanical stirring. In some embodiments, the stirring is performed at a speed of 200-400 rpm for 20-40 min.

[0022] In some embodiments, the application is performed by conventional brushing or spraying.

[0023] In some embodiments, the gradient heating method is used, specifically, heating to 80-100 DEG C, holding for 2-10 hours, then heating to 120-160 DEG C, holding for 2-10 hours, and then heating to 200-240 DEG C, holding for 2-10 hours.

[0024] The present application has the following advantages:

[0025] The material provided by the present application comprises fluorosilicone resin prepolymer, nano rubber, aerogel powder, inorganic fiber, ceramic particles and silane coupling agent, wherein: a, the fluorine side chain contained in the structural unit of formula (1) of the fluorosilicone resin prepolymer reduces the intermolecular force, increases phonon scattering, and provides flexibility and low thermal conductivity; the bulky phenyl group contained in the structural unit of formula (3) destroys the chain regularity, improves the rigidity and high temperature resistance; the structural unit of formula (2) as a crosslinking point, improves the crosslinking density, resists plastic deformation, and can condense with the remaining Si-OR in curing to build a three-dimensional network.b, the nano rubber induces silver shear band (consumes energy), the inorganic fiber bridges the cracks, the three-dimensional network disperses the stress, the ceramic particles provide hard phase to improve wear resistance, the aerogel improves heat insulation, and the silane coupling agent as an interfacial modifier improves the compatibility of organic / inorganic phases.c, by molecular design of the fluorosilicone resin matrix combined with multi-component synergistic modification, a metal surface coating with high wear resistance, low thermal conductivity and high toughness can be prepared, which is particularly suitable as a surface coating material for drill pipe for oil well drilling, and meets the stability requirements under extreme chemical and high temperature conditions. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The photos of the coating integrated component samples prepared for the examples are shown, wherein, from left to right, they are the sample of example 1, the sample of example 2 and the sample of example 3. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application is described clearly and completely below, obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0028] In the following examples, the particle size of the nano rubber is 50-500 nm; the average particle size of the aerogel powder is 10-100 microns; the diameter of the inorganic fiber is 5-10 microns; and the particle size of the ceramic particles is 2-20 microns, all of which are commercially available products.

[0029] Example 1

[0030] (1) Methyl trifluoropropyl siloxane, phenyl siloxane and tetraethoxysilane were mixed with ethanol, water and dibutyltin dilaurate in a molar ratio of 6:3:1, the addition amount of ethanol was 60% of the total mass of the three monomers, the addition amount of water was 2% of the total mass of the three monomers, and the addition amount of dibutyltin dilaurate was 0.1% of the total mass of the three monomers, heated to 80°C for 2h to obtain a fluorosilicon resin prepolymer;

[0031] (2) 5 parts by weight of nano hydrogenated nitrile rubber, 0.1 parts by weight of silica aerogel powder, 5 parts by weight of short quartz fiber, 20 parts by weight of alumina ceramic particles, and 0.5 parts by weight of γ-aminopropyl triethoxysilane were uniformly dispersed into 100 parts by weight of the fluorosilicon resin prepolymer prepared in step (1) by mechanical stirring (speed 300 rpm, time 30 min) to obtain a coating slurry;

[0032] (3) The slurry obtained in step (2) was sprayed onto the surface of 304 stainless steel by spraying process, and the coating thickness was 1mm, then it was placed in an oven, first heated from room temperature to 80°C at a heating rate of 2°C / min, and kept for 10h, then heated to 120°C at a heating rate of 2°C / min, and kept for 10h, then heated to 200°C at a heating rate of 2°C / min, and kept for 10h, and then cooled to room temperature in the oven, and the obtained coating integrated component is shown as the left sample in Figure 1 .

[0033] Example 2

[0034] (1) Methyl trifluoropropyl siloxane, phenyl siloxane and tetraethoxysilane were mixed with isopropanol, water and dibutyltin dilaurate in a molar ratio of 3:6:1, the addition amount of isopropanol was 150% of the total mass of the three monomers, the addition amount of water was 2.7% of the total mass of the three monomers, and the addition amount of dibutyltin dilaurate was 0.3% of the total mass of the three monomers, heated to 80°C for 2h to obtain a fluorosilicon resin prepolymer;

[0035] (2) 20 parts by weight of nano cis-butadiene rubber, 1 part by weight of silicon carbide aerogel powder, 40 parts by weight of short basalt fiber, 10 parts by weight of silicon carbide ceramic particles, and 5 parts by weight of γ-aminopropyl triethoxysilane were uniformly dispersed into 100 parts by weight of the fluorosilicon resin prepolymer prepared in step (1) by mechanical stirring (speed 300 rpm, time 30 min) to obtain a coating slurry;

[0036] (3) The slurry obtained in step (2) is sprayed onto the surface of 304 stainless steel by spraying process, the coating thickness is 1 mm, then it is placed in an oven, first heated from room temperature to 100°C at a heating rate of 2°C / min, kept for 2h, then heated to 160°C at a heating rate of 2°C / min, kept for 2h, then heated to 240°C at a heating rate of 2°C / min, kept for 2h, and then cooled to room temperature in the oven, the obtained coating integrated component is shown as the right sample in FIG. 1. The coating thermal conductivity is 0.137 W / (m·K), and the temperature resistance is 210°C. Figure 1

[0037] Example 3

[0038] (1) Methyl trifluoropropyl siloxane, phenyl siloxane and tetraethoxysilane are mixed with ethanol, water and tetrabutyl titanate at a molar ratio of 8:4:2, the addition amount of ethanol is 90% of the total mass of the three monomers, the addition amount of water is 1.5% of the total mass of the three monomers, and the addition amount of tetrabutyl titanate is 1% of the total mass of the three monomers, heated to 80°C for 2h to obtain a fluorosilicon resin prepolymer;

[0039] (2) 10 parts by weight of nano chlorobutyl rubber, 2 parts by weight of silica aerogel powder, 20 parts by weight of chopped basalt fiber, 15 parts by weight of silicon carbide ceramic particles, and 2 parts by weight of γ-aminopropyl triethoxysilane are uniformly dispersed into 100 parts by weight of the fluorosilicon resin prepolymer prepared in step (1) by mechanical stirring (rotating speed 300 rpm, time 30 min) to obtain a coating slurry;

[0040] (3) The slurry obtained in step (2) is brushed onto the surface of 304 stainless steel by brushing process, the coating thickness is 1 mm, then it is placed in an oven, first heated from room temperature to 90°C at a heating rate of 2°C / min, kept for 5h, then heated to 150°C at a heating rate of 2°C / min, kept for 5h, then heated to 220°C at a heating rate of 2°C / min, kept for 8h, and then cooled to room temperature in the oven, the obtained coating integrated component is shown as the right sample in FIG. 1. The coating thermal conductivity is 0.137 W / (m·K), and the temperature resistance is 210°C. Figure 1

[0041] Comparative Example 1

[0042] The difference from Example 2 is only that in step (1), the phenyl siloxane is removed.

[0043] Comparative Example 2

[0044] The difference from Example 2 is only that in step (1), the tetraethoxysilane is removed.

[0045] Comparative Example 3 ​​

[0046] The difference from Example 2 is only that in step (1), methyl trifluoropropyl siloxane, phenyl siloxane, and tetraethoxysilane are mixed in a molar ratio of 8:2:1.

[0047] Comparative Example 4

[0048] The difference from Example 2 is only that in step (1), methyl trifluoropropyl siloxane, phenyl siloxane, and tetraethoxysilane are mixed in a molar ratio of 3:6:6.

[0049] Comparative Example 5

[0050] The difference from Example 2 is only that in step (3), the slurry obtained in step (2) is sprayed onto the surface of 304 stainless steel with a coating thickness of 1 mm, and then placed in an oven, heated to 240°C at a heating rate of 2°C / min, and held for 2 h, and then cooled to room temperature in the oven.

[0051] Comparative Example 6

[0052] The difference from Example 2 is only that in step (3), the slurry obtained in step (2) is sprayed onto the surface of 304 stainless steel with a coating thickness of 1 mm, and then placed in an oven, first heated to 160°C at a heating rate of 2°C / min from room temperature, held for 2 h, and then heated to 240°C at a heating rate of 2°C / min, held for 2 h, and then cooled to room temperature in the oven.

[0053] The samples prepared in the above examples and comparative examples were subjected to various performance tests, and the results are shown in Tables 1 and 2:

[0054] Table 1 Performance test results of Examples 1-3

[0055]

[0056] Table 2 Performance test results of Comparative Examples 1-6

[0057]

[0058] Based on the above test results, (1) the molar ratio of methyl trifluoropropyl siloxane, phenyl siloxane, and tetraethoxysilane is controlled in the range of 3-8:3-6:1-2, and the coating obtained has the characteristics of good wear resistance, high adhesion, good impact resistance, low thermal conductivity, and good flexibility. When the molar ratio of the three monomers is not in the above range or only two of the three monomers are used, the performance will deteriorate sharply.

[0059] (2) Stepwise heating allows the solvent / small molecules to volatilize step by step, and the crosslinked network grows in order, avoiding the accumulation of internal stress, which is beneficial to the formation of a complete crosslinked network and the obtaining of a coating with no cracks and good wear resistance.

[0060] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details of the above-described embodiments. Various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

Claims

1. A drilling tool for oil well drilling, characterized in that, It includes a substrate and a coating formed on at least a portion of the surface of the substrate, wherein the coating is made of a low thermal conductivity, high strength and toughness modified fluorosilicone resin coating material, which includes fluorosilicone resin prepolymer, nano rubber, aerogel powder, inorganic fiber, ceramic particles and silane coupling agent. The fluorosilicone resin prepolymer is composed of structural unit a as shown in formula (1), structural unit b as shown in formula (2), and structural unit c as shown in formula (3): Where m is an integer from 0 to 2, x, y, and z are the number of moles, and x:y:z = 3~8:1~2:3~6, and R1 is hydrogen, methyl, or phenyl; Based on 100 parts of the total weight of the fluorosilicone resin prepolymer, the content of the nano-rubber is 5-20 parts by weight, the content of the aerogel powder is 0.1-2 parts by weight, the content of the inorganic fiber is 5-40 parts by weight, the content of the ceramic particles is 10-20 parts by weight, and the content of the silane coupling agent is 0.5-5 parts by weight.

2. The drilling tool for oil well drilling according to claim 1, characterized in that, The nano-rubber is any one or a mixture of two or more of hydrogenated nitrile rubber, cis-butadiene rubber, chloroprene rubber or isoprene rubber; And / or, the aerogel is any one or a mixture of two or more of silica aerogel, silicon carbide aerogel, aluminum oxide aerogel or zirconium dioxide aerogel; And / or, the inorganic fiber is any one or a mixture of two or more of chopped quartz fiber, basalt fiber or glass fiber; And / or, the ceramic particles are any one or a mixture of two of alumina ceramic particles and silicon carbide ceramic particles; And / or, the silane coupling agent is an aminosilane coupling agent.

3. The drilling tool for oil well drilling according to claim 2, characterized in that, The aminosilane coupling agent is either γ-aminopropyltriethoxysilane or γ-aminopropyltrimethoxysilane.

4. The drilling tool for oil well drilling according to claim 2, characterized in that, The particle size of the nano-rubber is 50~500nm; And / or, the average particle size of the aerogel powder is 10~100 μm; And / or, the diameter of the inorganic fiber is 5~10 μm; And / or, the particle size of the ceramic particles is 2~20 μm.

5. The drilling tool for oil well drilling according to claim 1, characterized in that, The substrate is alloy steel.

6. The method for preparing drilling tools for oil well drilling according to claim 1, characterized in that, The preparation method includes: Provide base materials; A slurry is formed by mixing fluorosilicone resin prepolymer, nano-rubber, aerogel powder, inorganic fiber, ceramic particles and silane coupling agent; Applying a slurry to at least a portion of the surface of a substrate; and, Heating solidifies the slurry on the surface of the substrate to obtain the drilling tool for oil well drilling.

7. The preparation method according to claim 6, characterized in that, The heating process involves first heating to 80-100℃ and holding for 2-10 hours, then heating to 120-160℃ and holding for 2-10 hours, and finally heating to 200-240℃ and holding for 2-10 hours.

Images