A kind of shear-resistant adhesive for sucker rod and its preparation method

Abstract

The application belongs to the technical field of adhesive, and provides a shear-resistant adhesive for sucker rod and a preparation method thereof.The method comprises the following steps: S1, mixing 100 parts of epoxy resin and 25-28 parts of polyurethane by weight, and uniformly melting at 80 DEG C to obtain a melt;S2, adding 6.3-6.7 parts of modified titanium dioxide, 1.3-1.5 parts of nitric acid-oxidized modified carbon fiber and 1.6-1.8 parts of aniline-dicyandiamide modifier into the melt obtained in S1, and ultrasonic stirring and stirring until dissolved, and then cooling to 50±2 DEG C to obtain a mixture;S3, adding 75-77 parts of methyltetrahydrophthalic anhydride and 0.6-0.8 parts of imidazole into the mixture obtained in S2 in sequence, and uniformly mixing to obtain the shear-resistant adhesive for sucker rod.The shear strength of the adhesive prepared by the application can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a shear-resistant adhesive for sucker rods and its preparation method. Background Technology

[0002] The sucker rod is a key component in oilfield rod pump production systems, primarily used to transmit power from the surface pumping unit to the downhole pump. After mechanical fixing of the sucker rod to its associated tools such as the centralizer or piston, adhesive is used to further secure it, enhancing its stability. Due to its complex operating environment (enduring alternating loads, corrosive media, and abrasion), the application of adhesive is crucial for improving the sucker rod's reliability and extending its service life.

[0003] A Chinese invention patent with publication number CN 116463091A discloses a two-component weather-resistant epoxy adhesive and its preparation method. In the preparation of this epoxy adhesive, titanium dioxide microparticles are introduced. TiO2 is known to possess excellent photostability and chemical inertness, effectively absorbing and scattering ultraviolet light, slowing down the degradation process of polymer materials under light irradiation, thereby improving anti-aging properties. Furthermore, the addition of TiO2 can improve the density of the adhesive, reduce the penetration paths of moisture, oxygen, and corrosive media, and thus improve corrosion resistance. However, excessive addition of nano-TiO2 (>3%) can lead to a decrease in the shear strength of the resulting adhesive. Summary of the Invention

[0004] To address the problems existing in the background art, the present invention provides a shear-resistant adhesive for sucker rods and its preparation method, which can effectively improve the shear strength of the prepared adhesive.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a shear-resistant adhesive for sucker rods, comprising the following steps: S1. By weight, 100 parts of epoxy resin and 25-28 parts of polyurethane are mixed and melted uniformly at 80°C to obtain a melt. S2. Add 6.3-6.7 parts of modified titanium dioxide, 1.3-1.5 parts of nitric acid oxidized modified carbon fiber, and 1.6-1.8 parts of aniline-dicyandiamide modifier to the melt obtained in S1. After sonication and stirring until dissolved, cool to 50±2℃ to obtain a mixture. S3. Add 75-77 parts of methyltetrahydrophthalic anhydride and 0.6-0.8 parts of imidazole to the mixture obtained in S2 in sequence, mix well, and the shear-resistant adhesive for sucker rods is obtained.

[0006] Furthermore, the preparation method of the nitric acid oxidized modified carbon fiber is as follows: carbon fiber and concentrated nitric acid are mixed and stirred at a mass ratio of 1:5, reacted at room temperature for 6-8 hours, vacuum filtered, washed with deionized water until neutral, and dried to obtain the nitric acid oxidized modified carbon fiber.

[0007] Furthermore, the concentrated nitric acid has a mass fraction of 65-68%.

[0008] Furthermore, the drying temperature is 75-78℃, and the drying time is 6-7 hours.

[0009] Further, the preparation method of the aniline-dicyandiamide modified product is as follows: 0.19-0.21 mol of dicyandiamide, 0.19-0.21 mol of aniline, 30-35 mL of water and 16-20 mL of concentrated hydrochloric acid (36.5 wt%) are added to a flask, the mixture is heated and stirred, and after the reaction, the reaction product is filtered, washed with water and dried to obtain the aniline-dicyandiamide modified product.

[0010] Furthermore, the molar ratio of dicyandiamide to aniline is 1:1.

[0011] Furthermore, the reaction temperature is 88-90℃, and the reaction time is 3 hours.

[0012] Further, the preparation method of the modified titanium dioxide is as follows: 0.4-0.45g of titanate and 20mL of toluene are added to a flask and mixed. After stirring evenly at 25°C, a mixed solution is obtained. 10g of nano titanium dioxide is added to the mixed solution and ultrasonically stirred at 80°C for 3-3.5h. The mixture is then filtered, washed repeatedly with toluene reagent, dried once, ground, and dried a second time to obtain the final product.

[0013] Furthermore, the temperature for the first drying is 80±2℃ and the time is 4-4.5h; the temperature for the second drying is 80±2℃ and the time is 3-3.2h.

[0014] Secondly, the present invention provides a shear-resistant adhesive for sucker rods, which is prepared by the above-described preparation method.

[0015] This application has the following beneficial effects: In the preparation of the shear-resistant adhesive for sucker rods in this invention, nitric acid-oxidized carbon fibers and aniline-dicyandiamide modifiers are simultaneously introduced. The benzene ring structure of the aniline-dicyandiamide modifier imparts rigidity, while the flexible amino segments can insert into the TiO2 agglomeration region, encapsulating nanoscale defects and inhibiting crack propagation, thereby increasing the density and reducing the porosity of the adhesive layer, thus reducing the initiation of stress concentration points and improving shear strength.

[0016] Meanwhile, the aniline-dicyandiamide modified molecular chain retains multiple active amino groups (-NH2), which can undergo amidation reaction with the carboxyl groups on the carbon fiber surface and crosslink with the epoxy groups of epoxy resin to form a gradient transition layer of "carbon fiber-aniline-dicyandiamide-epoxy resin". This process can eliminate the interface defects generated when nitric acid is introduced to oxidize and modify carbon fibers alone, and transform the weak interface that would originally lead to brittle fracture into a tough interface with strong covalent bonds, thereby synergistically improving shear strength. Attached Figure Description

[0017] Figure 1 A comparative trend chart of the shear strength data of the adhesives prepared in Examples 1-3 and Comparative Examples 1-3 in the experimental examples of this invention. Detailed Implementation

[0018] The present application will be further described in detail below with reference to the embodiments.

[0019] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0020] In the following examples and comparative examples, the preparation method of nitric acid oxidative modified carbon fiber is as follows: Carbon fiber and concentrated nitric acid with a mass fraction of 67% are mixed and stirred at a mass ratio of 1:5 to ensure that the carbon fiber is fully immersed in concentrated nitric acid, providing a sufficient oxidative environment for the reaction and avoiding uneven local reaction. After reacting at room temperature for 7 hours, solid-liquid separation is achieved by vacuum filtration, followed by repeated rinsing with deionized water until the pH value of the filtrate stabilizes at around 7, showing neutrality. Then, it is dried at 76°C for 6.5 hours; the temperature setting of 76°C can efficiently remove moisture from the surface of carbon fiber, avoid high temperature damage to the oxygen-containing functional groups introduced on the surface of carbon fiber, and prevent the internal structure of carbon fiber from denaturing due to excessive temperature; the drying time of 6.5 hours can ensure complete removal of moisture and ensure uniform drying of the product; thus, nitric acid oxidative modified carbon fiber is obtained.

[0021] The preparation method of aniline-dicyandiamide modified product is as follows: 0.2 mol of dicyandiamide and 0.2 mol of aniline were accurately weighed and slowly added to a clean flask, followed by 32 mL of water and 16.8 mL of concentrated hydrochloric acid (36.5 wt%). During the addition process, the operation was slow to prevent splashing, and the stirring was started and continuously stirred at 280 r / min to ensure that the dicyandiamide and aniline were fully dispersed and dissolved in the mixed solvent of water and concentrated hydrochloric acid to form a homogeneous reaction system. The reaction system was then heated to 89℃, and stirred continuously at 280 r / min at 89℃ for 3 hours. After the reaction, the reaction product was filtered, washed repeatedly with deionized water until the pH of the filtrate was 7, and then dried in a vacuum drying oven at 70℃ for 6 hours to obtain the aniline-dicyandiamide modified product.

[0022] The modified titanium dioxide was prepared as follows: 0.42 g of titanate and 20 mL of toluene were added to a flask and mixed. The mixture was stirred at 25 °C until homogeneous to obtain a solution. Titanate, as the key modifier, has active groups in its molecular structure that can chemically bond with the hydroxyl groups on the surface of nano-titanium dioxide in subsequent reactions, thus achieving surface modification of titanium dioxide. 10 g of nano-titanium dioxide was added to the solution, and the mixture was ultrasonically stirred at 80 °C for 3.2 h. The mixture was then filtered, washed three times with toluene, dried at 80 °C for 4.2 h, ground, and dried at 80 °C for 3 h to obtain the modified titanium dioxide.

[0023] Example 1: This example provides a method for preparing a shear-resistant adhesive for sucker rods, comprising the following steps: S1. Mix 100 parts of epoxy resin and 27 parts of polyurethane by weight, and melt them uniformly at 80°C to obtain a melt.

[0024] Specifically, a clean, dry three-necked flask was placed in a thermostatically heated magnetic stirrer. First, 100 parts by weight of bisphenol A epoxy resin (E-51) were added, and stirring was started at 200 rpm. The temperature was slowly increased to 80°C. After the epoxy resin was completely melted and had good fluidity, 27 parts by weight of polyurethane were added, ensuring uniform contact between the two resins and avoiding localized agglomeration. The temperature was maintained at 80°C, and the stirring speed was increased to 350 rpm. Stirring was continued for 30 minutes to form a homogeneous molten system, yielding the melt.

[0025] S2. Add 6.5 parts of modified titanium dioxide, 1.4 parts of nitric acid oxidized modified carbon fiber, and 1.7 parts of aniline-dicyandiamide modifier to the melt obtained in S1. During the feeding process, stir continuously at a speed of 300 r / min. After the feeding is completed, turn on ultrasonic stirring with an ultrasonic power of 300 W, an ultrasonic frequency of 40 kHz, and increase the stirring speed to 350 r / min. The ultrasonic stirring time is 35 min. After the ultrasonic stirring is completed, turn off the heating and slowly cool to 50 °C at a cooling rate of 5 °C / min to obtain the mixture.

[0026] S3. Add 76 parts of methyltetrahydrophthalic anhydride and 0.7 parts of imidazole to the mixture obtained in S2 in sequence, and stir at 300 r / min for 25 min to mix evenly, thus obtaining the shear-resistant adhesive for sucker rods.

[0027] Example 2: The difference between this example and Example 1 is that: a method for preparing a shear-resistant adhesive for sucker rods includes the following steps: S1. Mix 100 parts of epoxy resin and 25 parts of polyurethane by weight, and melt them uniformly at 80°C to obtain a melt.

[0028] S2. Add 6.3 parts of modified titanium dioxide, 1.3 parts of nitric acid oxidized modified carbon fiber and 1.6 parts of aniline-dicyandiamide modifier to the melt obtained in S1. After sonication and stirring until dissolved, cool to 50°C to obtain a mixture.

[0029] S3. Add 75 parts of methyltetrahydrophthalic anhydride and 0.6 parts of imidazole to the mixture obtained in S2 in sequence, mix well, and the shear-resistant adhesive for sucker rods is obtained.

[0030] Example 3: The difference between this example and Example 1 is that: a method for preparing a shear-resistant adhesive for sucker rods includes the following steps: S1. Mix 100 parts of epoxy resin and 28 parts of polyurethane by weight, and melt them uniformly at 80°C to obtain a melt.

[0031] S2. Add 6.7 parts of modified titanium dioxide, 1.5 parts of nitric acid oxidized modified carbon fiber, and 1.8 parts of aniline-dicyandiamide modifier to the melt obtained in S1. After sonication and stirring until dissolved, cool to 50°C to obtain a mixture.

[0032] S3. Add 77 parts of methyltetrahydrophthalic anhydride and 0.8 parts of imidazole to the mixture obtained in S2 in sequence, mix well, and the shear-resistant adhesive for sucker rods is obtained.

[0033] Comparative Example 1: The difference between this comparative example and Example 1 is that no nitric acid oxidized modified carbon fiber and aniline-dicyandiamide modifier are added in the preparation of the shear-resistant adhesive for the sucker rod.

[0034] Specifically, a method for preparing a shear-resistant adhesive for sucker rods includes the following steps: S1. Mix 100 parts of epoxy resin and 27 parts of polyurethane by weight, and melt them uniformly at 80°C to obtain a melt.

[0035] S2. Add 6.5 parts of modified titanium dioxide to the melt obtained in S1, sonicate and stir until dissolved, then cool to 50°C to obtain a mixture.

[0036] S3. Add 76 parts of methyltetrahydrophthalic anhydride and 0.7 parts of imidazole to the mixture obtained in S2 in sequence, mix well, and the shear-resistant adhesive for sucker rods is obtained.

[0037] Comparative Example 2: The difference between this comparative example and Example 1 is that no aniline-dicyandiamide modifier is added in the preparation of the shear-resistant adhesive for the sucker rod.

[0038] Specifically, a method for preparing a shear-resistant adhesive for sucker rods includes the following steps: S1. Mix 100 parts of epoxy resin and 27 parts of polyurethane by weight, and melt them uniformly at 80°C to obtain a melt.

[0039] S2. Add 6.5 parts of modified titanium dioxide and 1.4 parts of nitric acid-oxidized modified carbon fiber to the melt obtained in S1, sonicate and stir until dissolved, and then cool to 50°C to obtain a mixture.

[0040] S3. Add 76 parts of methyltetrahydrophthalic anhydride and 0.7 parts of imidazole to the mixture obtained in S2 in sequence, mix well, and the shear-resistant adhesive for sucker rods is obtained.

[0041] Comparative Example 3: The difference between this comparative example and Example 1 is that nitric acid oxidized modified carbon fiber is not added in the preparation of the shear-resistant adhesive for the sucker rod.

[0042] Specifically, a method for preparing a shear-resistant adhesive for sucker rods includes the following steps: S1. Mix 100 parts of epoxy resin and 27 parts of polyurethane by weight, and melt them uniformly at 80°C to obtain a melt.

[0043] S2. Add 6.5 parts of modified titanium dioxide and 1.7 parts of aniline-dicyandiamide modifier to the melt obtained in S1, sonicate and stir until dissolved, and then cool to 50°C to obtain a mixture.

[0044] S3. Add 76 parts of methyltetrahydrophthalic anhydride and 0.7 parts of imidazole to the mixture obtained in S2 in sequence, mix well, and the shear-resistant adhesive for sucker rods is obtained.

[0045] Experimental Example: Test Subjects: Adhesives prepared in Examples 1-3 and Comparative Examples 1-3. Test Items and Methods: After allowing the adhesives to stand and removing air bubbles from the adhesive solution through vacuum, the treated adhesive solution was applied to a prepared mold. Specifically, the mold was cleaned with acetone, then placed in an 80℃ oven for 1 hour, and a thin layer of vacuum silicone grease was evenly applied to the inside of the mold. The mold was then placed in an oven for gradient temperature curing: 80℃ for 2 hours; 120℃ for 1 hour; 150℃ for 1 hour; 180℃ for 1 hour. After curing, the oven was closed, and the mixture was allowed to cool naturally to room temperature. The tensile shear strength of the composite material was then tested using an electronic universal testing machine. Test Results: See Table 1.

[0046] Table 1. Experimental Results Data for the Experimental Case

[0047] Results Analysis: Combining the data in Table 1 and... Figure 1 Analysis of Examples 1-3 shows that the shear strength test data of the adhesive prepared by the present invention is as high as 27.98 MPa or more.

[0048] Combining the data in Table 1 and Figure 1 Analysis of Example 1 and Comparative Examples 1-3: Specifically, by comparing Comparative Example 1 and Comparative Example 2, it can be seen that, compared with Comparative Example 1, the shear strength test data of the adhesive prepared by simply adding nitric acid oxidation-modified carbon fiber in Comparative Example 2 decreased from 27.10 MPa (Comparative Example 1) to 26.74 MPa (Comparative Example 2). This indicates that simply adding nitric acid oxidation-modified carbon fiber can actually lead to a decrease in the shear strength of the adhesive.

[0049] This is mainly because nanoscale microcracks already exist in the TiO2 content > 3% system due to the agglomeration of modified TiO2 (nanoscale); at this time, the introduction of nitric acid to oxidize and modify carbon fibers causes the highly active groups on the fiber surface to react preferentially with the resin, consuming some epoxy groups and resulting in an imbalance of local crosslinking density; moreover, the fiber itself has high rigidity, and uneven dispersion will form new stress concentration points near the TiO2 agglomeration area, triggering early cracking and further reducing shear strength.

[0050] Specifically, by comparing Comparative Example 1 and Comparative Example 3, it can be seen that, compared with Comparative Example 1, the shear strength test data of the adhesive prepared by Comparative Example 3, which only introduced aniline-dicyandiamide modifier, increased from 27.10 MPa (Comparative Example 1) to 27.69 MPa (Comparative Example 3), indicating that the shear strength of the adhesive prepared by only introducing aniline-dicyandiamide modifier can be improved.

[0051] In comparison with Example 1, it can be seen that the simultaneous introduction of nitric acid oxidized modified carbon fiber and aniline-dicyandiamide modifier can produce a synergistic effect, synergistically improving the shear strength of the prepared adhesive.

[0052] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0053] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a shear-resistant adhesive for sucker rods, characterized in that, Includes the following steps: S1. By weight, mix 100 parts of epoxy resin and 25-28 parts of polyurethane, melt them evenly, and obtain a melt. S2. Add 6.3-6.7 parts of modified titanium dioxide, 1.3-1.5 parts of nitric acid oxidized modified carbon fiber, and 1.6-1.8 parts of aniline-dicyandiamide modifier to the melt obtained in S1. After sonication and stirring until dissolved, cool to 50±2℃ to obtain a mixture. S3. Add 75-77 parts of methyltetrahydrophthalic anhydride and 0.6-0.8 parts of imidazole to the mixture obtained in S2 in sequence, mix well, and the shear-resistant adhesive for sucker rods is obtained. The modified titanium dioxide is prepared as follows: 0.4-0.45g of titanate and 20mL of toluene are added to a flask and mixed. The mixture is stirred evenly at 25°C to obtain a mixed solution. 10g of nano titanium dioxide is added to the mixed solution and ultrasonically stirred at 80°C for 3-3.5h. The mixture is then filtered, washed, dried once, ground, and dried a second time to obtain the final product. The preparation method of the aniline-dicyandiamide modified product is as follows: 0.19-0.21 mol of dicyandiamide, 0.19-0.21 mol of aniline, 30-35 mL of water and 16-20 mL of concentrated hydrochloric acid are added to a flask, the mixture is heated and stirred, and after the reaction, the reaction product is filtered, washed with water and dried to obtain the product. The preparation method of the nitric acid oxidation modified carbon fiber is as follows: carbon fiber and concentrated nitric acid are mixed and stirred at a mass ratio of 1:5, reacted at room temperature for 6-8 hours, vacuum filtered, washed until neutral, and dried to obtain the product; the mass fraction of the concentrated nitric acid is 65-68%.

2. The method for preparing the shear-resistant adhesive for sucker rods according to claim 1, characterized in that, In the preparation of nitric acid oxidative modified carbon fiber, the drying temperature is 75-78℃ and the drying time is 6-7h.

3. The method for preparing the shear-resistant adhesive for sucker rods according to claim 1, characterized in that, The molar ratio of dicyandiamide to aniline is 1:

1.

4. The method for preparing the shear-resistant adhesive for sucker rods according to claim 1, characterized in that, In the preparation of aniline-dicyandiamide modified products, the reaction temperature is 88-90℃ and the reaction time is 3h.

5. The method for preparing the shear-resistant adhesive for sucker rods according to claim 1, characterized in that, The temperature for the first drying is 80±2℃ and the time is 4-4.5h; the temperature for the second drying is 80±2℃ and the time is 3-3.2h.

6. A shear-resistant adhesive for sucker rods, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 5.

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