Waterproof sealant for underwater pipes and preparation method thereof

Abstract

The invention relates to the technical field of sealants, and discloses a waterproof sealant for underwater pipes and a preparation method thereof, the sealant comprises the following components by weight: 100 parts of epoxy resin, 6-10 parts of an active diluent, 20-36 parts of an underwater curing agent, 8-20 parts of hyperbranched polyether amide and the like. The hyperbranched polyether amide disclosed by the invention contains flexible ether bonds, and amino groups contained in the hyperbranched polyether amide can participate in a curing reaction of epoxy resin, so that a good toughening effect on cured epoxy resin is achieved, and the impact strength and the toughness are improved. Meanwhile, the hyperbranched polyether amide contains a plurality of hydrophobic benzene ring structures, so that the epoxy resin can keep relatively low water absorption, and the waterproof performance of the sealant is favorably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sealants, and specifically to a waterproof sealant for underwater pipes and its preparation method. Background Technique

[0002] Due to its good bonding properties, mechanical strength, insulation, waterproof and anticorrosion properties, epoxy resin can be made into sealants, insulating adhesives, structural adhesives, etc., and has a wide range of applications in materials such as metal substrates, plastics, asphalt, and concrete. Underwater curing epoxy resin can be cured in water and is usually composed of a resin matrix, an underwater curing agent, fillers, etc. Traditional underwater curing epoxy resins and their sealant products will affect their bonding properties, toughness and other properties due to long-term contact with water. Therefore, it is necessary to improve the waterproofness, flexibility, bonding and other properties of epoxy resin.

[0003] Adding polymer modifiers such as polyphenylene ether, polyaryletherketone, hyperbranched polymers, etc. to epoxy resin can improve its toughness, heat resistance, waterproofness and other properties. Chinese patent document CN113717339B discloses a curing agent for reducing the volatile content of adhesives. Hyperbranched polyamidoamine is introduced into the amine curing agent by chemical modification to obtain a hyperbranched polymer-modified curing agent, which improves the tensile shear strength and other properties of epoxy resin adhesives. However, this patent does not solve the problems of poor toughness of epoxy resin and low bonding properties between plastics and pipes. Summary of the Invention

[0004] (1) Technical problems to be solved: Aiming at the deficiencies of the prior art, the present invention provides a waterproof sealant for underwater pipes and its preparation method, which solves the problems of low peel strength and poor toughness of epoxy resin sealants, and improves the waterproof performance of the sealant at the same time.

[0005] (2) Technical solution: A waterproof sealant for underwater pipes and its preparation method, including the following components in parts by weight: 100 parts of epoxy resin, 6 - 10 parts by weight of active diluent, 20 - 36 parts by weight of underwater curing agent, 8 - 20 parts by weight of hyperbranched polyether amide, 5 - 20 parts by weight of filler, 0.2 - 1 part by weight of dispersant, 0.6 - 1.2 parts by weight of defoaming agent. The preparation method is: adding active diluent, hyperbranched polyether amide, filler, dispersant, defoaming agent to epoxy resin, shearing and dispersing, and then adding underwater curing agent, stirring and mixing to obtain a waterproof sealant for underwater pipes.

[0006] Further, the filler is titanium dioxide, talc powder or montmorillonite.

[0007] Further, the active diluent is ethylene glycol diglycidyl ether or 1,4-butanediol diglycidyl ether.

[0008] Further, the preparation method of hyperbranched polyether amide is: (1) N-(3-aminopropyl)methacrylamide hydrochloride (CAS Registry Number: 72607-53-5) and an inorganic base were added to ethanol. After stirring, 4,4'-oxydibenzaldehyde (CAS Registry Number: 2215-76-1) was added. After stirring and reacting, the mixture was heated to volatilize, cooled in an ice-water bath, and a large amount of precipitate was formed. The precipitate was washed with water after filtration, and then recrystallized from dichloromethane to obtain the bisacrylamide monomer. The reaction formula is as follows: .

[0009] (2) The bisacrylamide monomer was added to methanol. After stirring, an aqueous solution of diethylenetriamine was added dropwise in an ice-water bath. After stirring, a polymerization reaction was carried out. The mixture was distilled under reduced pressure, washed successively with water and ethanol, and dried to obtain the hyperbranched polyether amide. The reaction formula is as follows: .

[0010] Further, the reaction temperature in (1) is 40 - 60 °C, and the reaction time is 5 - 8 h.

[0011] Further, the molar ratio of N-(3-aminopropyl)methacrylamide hydrochloride, inorganic base, and 4,4'-oxydibenzaldehyde in (1) is (2 - 2.2):(2 - 2.2):1.

[0012] Further, the inorganic base in (1) is sodium hydroxide or potassium hydroxide.

[0013] Further, the molar ratio of the bisacrylamide monomer and diethylenetriamine in (2) is 1:(1.1 - 1.2); Further, the polymerization reaction temperature in (2) is 65 - 80 °C, and during the reaction, reflux condensation is carried out, and the reaction time is 24 - 36 h.

[0014] (III) Beneficial technical effects: In the present invention, a hyperbranched polyether amide is obtained by carrying out a hyperbranched polymerization reaction between a bisacrylamide monomer containing a flexible ether bond and multiple hydrophobic benzene ring structures and diethylenetriamine, and then compounding it with epoxy resin, active diluent, underwater curing agent, filler, etc. to obtain a waterproof sealant for underwater pipes. The hyperbranched polyether amide contains active amino groups, which can replace part of the curing agent and react with epoxy resin to cure, thereby increasing the cohesive force of the sealant adhesive and being beneficial to improving the bonding performance.

[0015] The hyperbranched polyether amide of the present invention contains Schiff base groups, which can form coordination properties with the surface of stainless steel, thereby improving the bonding force and adhesion performance of the sealant to the stainless steel substrate. Moreover, the hyperbranched polyether amide contains amide bonds, which can form hydrogen bonds and other interaction forces with the amide bonds in the nylon 6 matrix, thus improving the bonding force and adhesion performance between the sealant and the nylon substrate. This enables the sealant to have good practical applications in the bonding and sealing of metal pipes such as stainless steel, and plastic pipes such as nylon and PVC.

[0016] The hyperbranched polyether amide of the present invention contains flexible ether bonds, and the amino groups contained can participate in the curing reaction of epoxy resin, thereby playing a good toughening role in the cured epoxy resin and improving the impact strength and toughness. At the same time, the hyperbranched polyether amide contains multiple hydrophobic benzene ring structures, which can keep the epoxy resin with a low water absorption rate, conducive to improving the waterproof performance of the sealant. Detailed implementation manners

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0018] The following epoxy resin model is E44, purchased from Nantong Changchen Chemical Co., Ltd. The underwater curing agent model is JA-IS, with an effective ingredient content of 95%, purchased from Sichuan Aopai Epoxy Additive Technology Co., Ltd. The nylon plastic model is LANXESS K224-G7, 35% glass fiber reinforced PA6, purchased from Shanghai Xianshun Plastic Co., Ltd. The dispersant model is BYK W966, purchased from Nanjing Quanxi New Materials Co., Ltd. The defoamer model is TEGO8030, purchased from Xuzhou Yihuiyang New Materials Co., Ltd.

[0019] Example 1 (1) Add 100 mmol of N-(3-aminopropyl) methacrylamide hydrochloride and 100 mmol of potassium hydroxide to 400 mL of ethanol. After stirring, add 50 mmol of 4,4'-oxydibenzaldehyde, heat to 60 °C, stir and react for 5 h, heat and volatilize, cool in an ice-water bath, a large amount of precipitate will precipitate. Filter and wash the precipitate with water, and then recrystallize in dichloromethane to obtain the bisacrylamide monomer.

[0020] (2) Add 50 mmol of the bisacrylamide monomer to 150 mL of methanol. After stirring, dropwise add 100 mL of an aqueous solution containing 55 mmol of diethylenetriamine in an ice-water bath. After stirring, heat to 70 °C and carry out a condensation reflux reaction for 24 h. Carry out vacuum distillation, wash with water and ethanol in turn, and dry to obtain the hyperbranched polyether amide.

[0021] (3) Add 7 g of reactive diluent ethylene glycol diglycidyl ether, 8 g of hyperbranched polyether amide, 14 g of talc powder, 0.7 g of dispersant, and 0.6 g of defoamer to 100 g of epoxy resin E44, shear and disperse, and then add 36 g of underwater curing agent, stir and mix to obtain a waterproof sealant for underwater pipes.

[0022] Example 2 (1) Add 110 mmol of N-(3-aminopropyl)methacrylamide hydrochloride and 110 mmol of sodium hydroxide to 400 mL of ethanol, stir, add 50 mmol of 4,4'-oxydibenzaldehyde, heat to 40 °C, stir and react for 8 h, heat and evaporate, cool in an ice-water bath, a large amount of precipitate will form, filter and wash the precipitate with water, and then recrystallize in dichloromethane to obtain the bisacrylamide monomer.

[0023] (2) Add 50 mmol of bisacrylamide monomer to 200 mL of methanol, stir, and dropwise add 120 mL of an aqueous solution containing 60 mmol of diethylenetriamine in an ice-water bath, stir, heat to 65 °C, condense and reflux for 36 h, distill under reduced pressure, wash with water and ethanol in turn, and dry to obtain hyperbranched polyether amide.

[0024] (3) Add 10 g of reactive diluent 1,4-butanediol diglycidyl ether, 12 g of hyperbranched polyether amide, 5 g of titanium dioxide, 0.2 g of dispersant, and 0.8 g of defoamer to 100 g of epoxy resin E44, shear and disperse, and then add 25 g of underwater curing agent, stir and mix to obtain a waterproof sealant for underwater pipes.

[0025] Example 3 (1) Add 50 mmol of bisacrylamide monomer to 200 mL of methanol, stir, and dropwise add 120 mL of an aqueous solution containing 60 mmol of diethylenetriamine in an ice-water bath, stir, heat to 80 °C, condense and reflux for 24 h, distill under reduced pressure, wash with water and ethanol in turn, and dry to obtain hyperbranched polyether amide.

[0026] (2) Add 6 g of reactive diluent ethylene glycol diglycidyl ether, 16 g of hyperbranched polyether amide, 20 g of montmorillonite, 1 g of dispersant, and 1.2 g of defoamer to 100 g of epoxy resin E44, shear and disperse, and then add 30 g of underwater curing agent, stir and mix to obtain a waterproof sealant for underwater pipes.

[0027] Example 4 (1) Add 50 mmol of bisacrylamide monomer to 150 mL of methanol. After stirring, add dropwise 100 mL of an aqueous solution containing 58 mmol of diethylenetriamine in an ice-water bath. After stirring, heat to 70 °C and carry out a condensation reflux reaction for 30 h. Then perform vacuum distillation, wash successively with water and ethanol, and dry to obtain hyperbranched polyether amide.

[0028] (2) Add 10 g of active diluent 1,4-butanediol diglycidyl ether, 20 g of hyperbranched polyether amide, 12 g of talcum powder, 0.6 g of dispersant, and 1.2 g of defoamer to 100 g of epoxy resin E44. Carry out shear dispersion, and then add 20 g of underwater curing agent and stir to mix to obtain a waterproof sealant for underwater pipes.

[0029] Comparative Example 1 (1) Add 7 g of active diluent ethylene glycol diglycidyl ether, 14 g of talcum powder, 0.7 g of dispersant, and 0.6 g of defoamer to 100 g of epoxy resin E44. Carry out shear dispersion, and then add 36 g of underwater curing agent and stir to mix to obtain a sealant for underwater pipes.

[0030] Comparative Example 2 (1) Prepare hyperbranched polyamide according to the method in the literature "Synthesis and Anti-collapse Mechanism Research of Hyperbranched Polymer HP-NH2" in the journal "Journal of Southwest Petroleum University (Natural Science Edition)", August 2021, Vol. 43, No. 4. Add 20 mmol of N,N-methylenebisacrylamide to 100 mL of water, add dropwise 22 mmol of diethylenetriamine, stir and react at 60 °C for 12 h, remove water by vacuum distillation to obtain hyperbranched polyamide.

[0031] (2) Add 7 g of active diluent ethylene glycol diglycidyl ether, 8 g of hyperbranched polyamide, 14 g of talcum powder, 0.7 g of dispersant, and 0.6 g of defoamer to 100 g of epoxy resin E44. Carry out shear dispersion, and then add 36 g of underwater curing agent and stir to mix to obtain a sealant for underwater pipes.

[0032] Comparative Example 3 (1) Add 100 mmol of N-(3-aminopropyl)methacrylamide hydrochloride and 100 mmol of potassium hydroxide to 350 mL of ethanol. After stirring, add 50 mmol of terephthalaldehyde, heat to 60 °C, stir and react for 5 h, heat to volatilize, cool in an ice-water bath, a large amount of precipitate will precipitate. Filter and wash the precipitate with water, and then recrystallize in dichloromethane to obtain bisacrylamide monomer. The structural formula is as follows: .

[0033] (2)50 mmol of bisacrylamide monomer was added to 150 mL of methanol. After stirring, an aqueous solution containing 55 mmol of diethylenetriamine was added dropwise in an ice-water bath. After stirring, the mixture was heated to 70 °C and refluxed for 24 h. Then, it was distilled under reduced pressure, washed successively with water and ethanol, and dried to obtain hyperbranched polyamide.

[0034] (3)7 g of the active diluent ethylene glycol diglycidyl ether, 8 g of hyperbranched polyamide, 14 g of talcum powder, 0.7 g of dispersant, and 0.6 g of defoamer were added to 100 g of epoxy resin E44. After shear dispersion, 36 g of underwater curing agent was added and stirred to obtain a sealant for underwater pipes.

[0035] The adhesion performance of the sealant to stainless steel was tested according to GB / T 7124-2008. The surfaces of two stainless steel substrates were polished. After being immersed in water, the sealant was applied, and the bonding was carried out. It was cured at 25 °C for 24 h. The stainless steel bonded specimens were taken out, placed at room temperature for 12 h, and then the tensile shear strength was tested.

[0036] The adhesion performance of the sealant to nylon plastic was tested. Two test pieces were molded from nylon plastic. The surfaces were polished and cleaned. After being immersed in water, the sealant was applied, and the bonding was carried out. It was cured at 25 °C for 24 h. The nylon plastic bonded specimens were taken out, placed at room temperature for 12 h, and then the tensile shear strength was tested.

[0037] The adhesion performance of the sealant to PVC board was tested. The surfaces of two PVC boards were polished and cleaned. After being immersed in water, the sealant was applied, and the bonding was carried out. It was cured at 25 °C for 24 h. The PVC bonded specimens were taken out, placed at room temperature for 12 h, and then the tensile shear strength was tested.

[0038] The sealant was poured into a mold and cured at 25 °C for 24 h to make a cured adhesive film specimen. The impact strength was tested according to GB / T 2567-2021.

[0039] The cured adhesive film specimen was made into a specimen with dimensions of 10 cm×10 cm×0.5 cm. After drying, it was weighed (denoted as m0), then placed in water and soaked at 70 °C for 72 h. The specimen was taken out, the surface moisture was wiped off, and then it was weighed (denoted as m). The water absorption rate W was calculated. W = (m - m0) / m0×100%.

[0040] Table 1 Performance Test of Sealant

[0041] After testing, the sealant of Comparative Example 1 has low tensile shear strength for stainless steel and nylon plastic, poor bonding performance, low impact strength, large water absorption rate, and poor toughness and waterproof performance. In the sealants of Examples 1-4, hyperbranched polyether amide is added, which contains active amino groups and can replace part of the curing agent to react with epoxy resin to cure, thereby increasing the cohesion of the sealant adhesive and being beneficial to improving the bonding performance. At the same time, the hyperbranched polyether amide contains Schiff base groups (-C=N-), which can form coordination properties with the surface of stainless steel, thereby improving the bonding force and bonding performance of the sealant adhesive to the stainless steel substrate, showing higher tensile shear strength, and also maintaining good bonding performance for polyvinyl chloride. And the hyperbranched polyether amide contains amide bonds, which can form intermolecular forces such as hydrogen bonds with the amide bonds in the nylon 6 matrix, thereby improving the bonding force and bonding performance between the sealant and the nylon substrate, showing higher tensile shear strength. At the same time, the hyperbranched polyether amide contains flexible ether bonds, and the active amino groups can participate in the curing reaction of epoxy resin, playing a good toughening role in the cured product, thereby improving the impact strength and toughness. The hyperbranched polyether amide contains multiple hydrophobic benzene ring structures, which can keep the epoxy resin with a low water absorption rate, thereby improving the waterproof performance of the sealant.

[0042] Compared with Example 1, in Comparative Example 2, N,N'-methylenebisacrylamide and diethylenetriamine are used for polymerization reaction, and the obtained hyperbranched polyamide contains active amino groups and can react with epoxy resin to cure, which is beneficial to improving the cohesion of the sealant and thus improving the bonding performance and tensile shear strength. However, this hyperbranched polyamide does not contain Schiff base structure and has weak coordination performance with the surface of stainless steel, resulting in poor bonding and adhesion ability of the sealant to stainless steel and low tensile shear strength. And the hyperbranched polyamide does not contain flexible ether bonds, and has poor toughening effect on the cured sealant, resulting in low impact strength. It also does not contain hydrophobic benzene ring structures, resulting in a large water absorption rate of the cured product and poor waterproof performance. In Comparative Example 3, terephthalaldehyde is used as the raw material, and the prepared bisacrylamide monomer and hyperbranched polyamide do not contain flexible ether bonds, and have poor toughening effect on the cured sealant, resulting in low impact strength. And the hydrophobic benzene ring structure is significantly less than that of the hyperbranched polyether amide in Example 1, resulting in a slightly higher water absorption rate of the cured sealant than that in Example 1 and poor waterproof performance.

[0043] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of the present technology, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A waterproof sealant for underwater pipes, characterized in that, The waterproof sealant for underwater pipes comprises the following components in parts by weight: 100 parts of epoxy resin, 6 - 10 parts by weight of reactive diluent, 20 - 36 parts by weight of underwater curing agent, 8 - 20 parts by weight of hyperbranched polyether amide, 5 - 20 parts by weight of filler, 0.2 - 1 part by weight of dispersant, 0.6 - 1.2 parts by weight of defoaming agent; The preparation method of the hyperbranched polyether amide is as follows: Add bisacrylamide monomer to methanol, stir, dropwise add an aqueous solution of diethylenetriamine in an ice - water bath, stir and then carry out a polymerization reaction, carry out vacuum distillation, wash successively with water and ethanol, and dry to obtain the hyperbranched polyether amide; The molar ratio of the bisacrylamide monomer to diethylenetriamine is 1:(1.1 - 1.2); the structural formula of the bisacrylamide monomer is as follows: .

2. The waterproof sealant for underwater pipe materials according to claim 1, characterized in that, The temperature of the polymerization reaction is 65 - 80 °C, and the reaction time is 24 - 36 h.

3. The waterproof sealant for underwater pipe materials according to claim 1, characterized in that The filler is titanium dioxide, talc powder or montmorillonite.

4. The waterproof sealant for underwater pipe materials according to claim 1, wherein, The reactive diluent is ethylene glycol diglycidyl ether or 1,4 - butanediol diglycidyl ether.

5. The waterproof sealant for underwater pipe materials according to claim 1, wherein The preparation method of the bisacrylamide monomer is as follows: Add N-(3 - aminopropyl) methacrylamide hydrochloride and inorganic base to ethanol, stir, then add 4,4'-oxybisbenzaldehyde, stir and react, heat to volatilize, cool in an ice - water bath, filter and wash with water, and recrystallize the product in dichloromethane to obtain the bisacrylamide monomer.

6. The waterproof sealant for underwater pipes according to claim 5, wherein In the preparation method of the bisacrylamide monomer, the reaction temperature is 40 - 60 °C, and the reaction time is 5 - 8 h.

7. The waterproof sealant for underwater pipe materials according to claim 5, characterized in that, The molar ratio of N-(3 - aminopropyl) methacrylamide hydrochloride, inorganic base, and 4,4'-oxybisbenzaldehyde is (2 - 2.2):(2 - 2.2):

1.

8. The waterproof sealant for underwater pipe materials according to claim 7, characterized in that, The inorganic base is sodium hydroxide or potassium hydroxide.

9. A method for preparing a waterproof sealant for underwater pipes according to any one of claims 1-8, characterized in that, The preparation method is as follows: Add the reactive diluent, hyperbranched polyether amide, filler, dispersant, and defoaming agent to the epoxy resin, carry out shear dispersion, then add the underwater curing agent, and stir and mix to obtain the waterproof sealant for underwater pipes.

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